US3608969A

US3608969A - Apparatus for controlling initial engagement of cutters with concrete pavement surfaces

Info

Publication number: US3608969A
Application number: US872494A
Authority: US
Inventors: Joseph B Fowkes
Original assignee: Christensen Diamond Products Co
Current assignee: Norton Christensen Inc
Priority date: 1969-10-30
Filing date: 1969-10-30
Publication date: 1971-09-28
Anticipated expiration: 1988-09-28

Abstract

A tractor or wheel loader carries a grooving unit, including a gang of rotating saw blades, for cutting parallel grooves in a concrete pavement. A shock absorber device prevents the saw blades from being lowered rapidly to impact against the pavement and thereby possibly damage the blades. The shock absorber device is initially lower than the blades and contacts the pavement first, gradually retracting to permit gradual lowering and engagement of the saw blades with the pavement.

Description

United States Patent Inventor Joseph B. Fowkes Salt Lake City, Utah Appl. No. 872,494

Filed Oct. 30, 1969 Patented Sept. 28, 1971 Assignee Christensen Diamond Products Company Salt Lake City, Utah APPARATUS FOR CONTROLLING INITIAL ENGAGEMENT OF CUTTERS WITH CONCRETE PAVEMENT SURFACES 24 Claims, 5 Drawing Figs.

US. Cl 299/39, 5 1/170 Int. Cl 1601c 23/09 Field of Search 299/39, 40 4 l; 5 1/176 [56] References Cited UNITED STATES PATENTS 982,759 1/1911 Bagalio 51/176X 3,266,846 8/1966 Luk'sch et a1. 299/39 3,414,327 12/1968 Austin 299/39 X Primary Examiner- Ernest R. Purser Attorney-Bernard Kriegel ABSTRACT: A tractor or wheel loader carries a grooving unit, including a gang of rotating saw blades, for cutting parallel grooves in a concrete pavement. A shock absorber device prevents the saw blades from being lowered rapidly to impact against the pavement and thereby possibly damage the blades. The shock absorber device is initially lower than the blades and contacts the pavement first, gradually retracting to permit gradual lowering and engagement of the saw blades with the pavement.

APPARATUS FOR CONTROLLING INITIAL ENGAGEMENT OF CU'I'IERS WITH CONCRETE PAVEMENT SURFACES The present invention relates to apparatus for cutting grooves in concrete and similar roadway surfaces, such as in highway and airport runways surfaces.

Apparatus has been provided for cutting grooves in concrete roadway surfaces. One such apparatus includes a gang of closely spaced rotating saw blades or discs that are moved along the roadway to cut shallow parallel grooves therein, to improve traction of vehicle and aircraft wheels thereagainst particularly during inclement weather. The particular four-wheel vehicle with a grooving cutter mechanism mounted thereon forms the subject matter of the application of Frank L. Christensen and Takeshi Mori, Ser. No. 851,193 filed Aug. 19, 1969 for Machines for Cutting Grooves in Concrete and Similar Roadway Surfaces. In such machine, the gang of saw blades is shiftable from a position elevated above the roadway surface into engagement therewith. It is, however, important to prevent the saw blades from being dropped accidentally or moving rapidly upon the pavement surface, since the impact could damage the saw blades. A gang of saw blades, with a matrix at their peripheral cutting portions containing diamonds, is expensive, a gang capable of grooving an overall pavement width of above feet costing in the neighborhood of $10,000.00

The present invention prevents accidental or too rapid lowering of the cutters of the grooving unit onto the pavement, controlling the vertical down feet of the cutters into the cutting position in the pavement or roadway. A shock absorber means is provided which first contacts the roadway and prevents engagement of the saw blades, or other cutters, therewith, retaining them a short distance above the roadway. After the shock absorber unit engages the roadway, it effects gradual lowering of the cutters into the cutting position, the shock absorber unit then being ineffective. Upon elevating of the cutter members from the roadway, the shock absorber unit automatically repositions itself to extend before the lowermost portion of the cutters, so that subsequent lowering of the grooving unit toward the pavement will again first contact the shock absorber unit therewith, followed by gradual lowering of the cutters the short distance necessary to bring them into appropriate cutting position with respect to the pavement.

More specifically, the shock absorber mechanism is operatively associated with the mechanism for raising and lowering the cutters into and from engagement with the pavement, such that elevating of the cutters from the pavement automatically extends the shock absorber mechanism so that it engages the pavement surface and prevents the cutters from bearing there against, after which the shock absorber, as noted above, automatically retracts to permit the gradual lowering of the cutters into their cutting position with respect to the pavement. If the lowering mechanism were to suddenly drop the grooving unit toward the pavement surface, the cutter blades could not contact the latter since the shock absorbers would first engage the surface, preventing the blades from contacting the latter. The cutting action then occurs without interference from the shock absorber mechanism. When the cutters are elevated from the pavement, the shock absorber is again automatically brought into its operative position in response to elevation of the cutter or grooving unit from the pavement.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense.

Referring to the drawings: FIG. 1 is a partially diagrammatic side elevational view of a machine embodying the invention, with its grooving unit elevated from a roadway surface and its shock absorber unit in extended position;

FIG. 2 is an enlarged side elevational view of a portion of the grooving unit, located in engagement with the roadway surface, with the shock absorber unit retracted, and a vehicle wheel raised from the roadway surface;

FIG. 3 is an enlarged cross section, taken along the line 3- 3 on FIG. 2;

FIG. 4 is an enlarged cross section, taken along the line 4- 4 on FIG. 2; and

FIG. 5 is a diagrammatic view-of the hydraulic system of the machine.

With the exception of the shock absorber mechanism and the hydraulic system illustrated in the drawings, the machine for cutting grooves S in concrete and similar roadway surfaces R is illustrated in the above-identified US. patent application. In view of such illustration and description only those portions of the apparatus will be described for the purpose of setting forth the present invention, since a complete description is unnecessary to its understanding. The machine includes a four wheel vehicle 10 which may be of a conventional tractor or wheel loader type manufactured by the Caterpillar Tractor Company. It has a main frame or chassis 11 with one set or a pair of steerable wheels 12 including pneumatic tires 13, which for steerable wheels 12 including pneumatic tires 13, which, for convenience, may be referred to as steerable front wheels, and another set or pair of wheels 14 including pneumatic rubber tires which, set or pair of wheels 14 for convenience, may be referred to as r ear wheels. The unit has the usual internal combustion engine 15, such as a diesel engine, that drives through a torque converter or other variable ratio transmission (not shown) to both the front and rear wheels to effect a four-wheel drive. The steerable wheels I2 are steered through a known mechanism by appropriate turning of a stee ring wheel 16 manipulated by the driver. A pair of spaced swing ro lift arms 17 are pivotally connected at their forward end portions to the upper part of the frame or chassis by hinge pins 18, the rear or lower ends of these arms being connected by pins 19 to the movable frame 20 of the grooving unit G of the machine. A pair of laterally spaced upper arms 21 are also connected by forward connector pins 22 to the swing arms I7 and by rear connector pins 23 to the movable frame 20 of the highway grooving unit.

The movable frame 20, which is disposed behind the rear wheels 14 of the machine, carries an internal combustion engine 24, such as a diesel engine, the crankshaft 25 of which rotates a shaft structure 26 through a suitable transmission, such as a belt and

pulley transmission

27, 28, 29, 30, rotatably supported in bearings fixed to the fame. The drive shaft structure 26 is suitably fixed to a saw blade assembly 31, comprising a plurality of saw discs or cutters 32 separated by spacers 33 and clamped to a mandrel 34 suitably attached to the drive shaft structure. The rim portion of each saw blade 32 may comprise a matrix of diamonds and other material for effectively cutting the concrete roadway surface. The saw blade or cutter assembly 31 may assume any required form, one such assembly being illustrated and described in the patent application of Warren 1. Hughes and Donald H. Mabcy, Scr. No. 788,838,, filed Jan. 3, I969, for Rotary Cutter Assembly.

As illustrated, the depths of penetration of the saw blades into the roadway surface, that is to say, the depth of cut of the parallel saw blades in producing the grooves S in the roadway surface, is determined by a pair of depth-of-cut rollers 35 located at opposite sides of the movable frame. Thus, a support arm 36 is pivotally mounted on the frame at each of its sides by a pivot pin 37, each arm having an axle 38 rotatably mounting a depth-of-cut roller 35 engageable with the roadway or airport runway surface R. The end of the support arm 36 opposite the pivot pin 37 is connected by means of a pin 39 to a generally vertically adjustable rod or shaft 40 having an upper threaded portion passing through a boss 41 fixed to the movable frame 20. Threadedly mounted on the threaded shaft portion and above and below the boss are nuts 42 bearing against washers 43 engaging the upper and lower surfaces of the boss. Appropriate turning of the nuts at each side of the frame will effect vertical adjustment of the shaft 40 to move the forward ends of the support arms up or down and shift the axes of the depth-of-cut rollers 35 with respect to the axis of the cutter shaft 26. The rollers 35 are located a desired distance above the lower periphery of the saw blades 32, thereby determining the depth of penetration of the saw bladed or cutters into the roadway surface R, which determines the depth of the grooves S cut into such surface. Following adjustment of the depth-of-cut rollers, the nut 42 are retightened against the washers 43 and the washers against the upper and lower sides of the bosses 41 to retain the depth-ofcut rollers in the position to which they have been adjusted.

The movable frame and saw blade assembly 31 and depth-of-cut rollers 35 carried thereby are shiftable as a unit in a vertical direction to bring the saw discs and rollers into and out of engagement with the pavement surface. The shifting or actuating mechanism includes a pair of laterally spaced cylinders 45 having lower ends connected hinge pins 46 to the frame or chasses 11 of the wheel loader vehicle. Each cylinder has a piston 47 slidable therein and secured to a piston rod 48 extending from the upper end of the cylinder and connected by a pin 49 to a swingable arm 17. The introduction of fluid under pressure into the head or lower ends 50 of the cylinders will shift the pistons 47 and piston rods 48 upwardly to swing the arms 17 and the entire movable frame 20 upwardly with respect to the roadway or pavement surface. On the other hand, the bleeding of fluid under pressure from the head ends of the cylinders and the introduction of such fluid under pressure into the upper or rod ends 51 of the cylinders will effect retraction of the piston rods 48 into the cylinders and downward movement of the swing arms 17 and the movable frame 20 to bring the depth-of-cut rollers 35 and the saw blades 32 downwardly. Prior to lowering of the grooving unit G, rotation of the saw blade assembly 31 by the internal combustion engine 24 on the frame is initiated, operating through the transmission 2730. The continued application of fluid under pressure into the rod ends 51 of the cylinders, after the shock absorber portion A of the grooving unit, described hereinbelow, has contacted the pavement, will effect elevation of the rear of the frame or chassis 11 and of the rear wheels 14 from the pavement surface. Thereafter, as set forth hereinbelow, the shock absorber unit A gradually retracts to slowly lower the rotating saw blades 32 and depth-of-cut 35 into contact with the pavement surface R. The weight of the wheel loader type of mechanism 10, to which the movable frame 20, saw blade assembly 31, and depth-of-cut roller mechanism has been secured, is quite large, and more than adequate for insuring penetration of the cutters 32 into the roadway surface to the desired depth, with the depth-of-cut rollers 35 engaging the roadway surface to limit the extent of penetration of the saw blades into the pavement.

Two shock absorber devices A are used being laterally spaced from one another. Each unit is carried by the movable frame 20. As shown, each unit includes a cylinder 60 mounted on the movable frame by a pin 61 passing through the upper end 62 of the cylinder and pivotally securing it to the frame 20 (FIG. 4). The cylinder has a piston 63 slidable therein secured to a piston rod 64 extending from the rod end 65 of the cylinder and connected by a pivot pin 66 to a support 67 pivoted upon the movable frame 20 by a hinge pin 68. The support carries an axle 69 rotatably mounting a pavement engaging wheel 70. When fluid under pressure is introduced into the upper or head ends 62 of the cylinders, the pistons 63 therein are moved downwardly to move the piston rods 64 downwardly and swing the supports 67 about their hinge pins 68 and thereby lower the wheels or rollers 70. When in their lower position, such rollers 70 will contact the pavement R, when the movable frame 20 is shifted downwardly, before the saw blades 32 can contact the pavement, the latter being prevented from engaging the pavement. When fluid under pressure is introduced into the rod ends 65 of the cylinders 60, the pistons 63 are elevated therein, which swing the supports 67 upwardly-and bring the rollers 70 upwardly to permit engagement of the saw blades 32 and depth-of-cut rollers 35 with the pavement. As described hereinbelow, such elevation or retraction of the supports 67, rollers 70, piston rods 64 and pistons 63 occurs gradually so that the rotating saw blades 32 are brought in a gradual manner into contact with the pavement R and into grooving relation to the pavement.

As illustrated, the vehicle or wheel loader 10 has a pump 71 driven constantly by the vehicle engine 15 when it is rotating, which draws a fluid or liquid, such as oil, from a supply tank 72 through a suction line 73a and delivers such fluid under high pressure to a discharge line 73 running to a three-position valve 74 mounted on the vehicle. A return line 75 extends from this valve to the supply tank 72 to return hydraulic fluid thereto. The three-position valve 74 is actuated by the operator through a control lever 76 and suitable linkage 77 running to the movable spool 78 of the three-position valve. A fluid pressure line 79 extends from one end of the three-position valve to a junction 80, another line 81 extending from this junction to the lower or head end 50 of each hydraulic lift cylinder 45. Another line 82 extends from this junction to the head end 62 of each of the shock absorber cylinders 60, each of these latter lines having a flow control valve 83 therein including a metering orifice 84 and a check valve 85 having a seat 87 and a ball 86 engageable therewith to permit free flow of fluid through the line 82 toward the cylinder 60, but which seats to preclude flow of fluid from the cylinder back towards the junction 80. Another line 88 extends from the three-position valve 74 to another junction 89. a fluid line 90 running from thisjunction to the rod end 51 of each cylinder 45. and a fluid line 91 from the junction 89 to the rod end 65 of each of the shock absorbing cylinders 60.

The hydraulic system is illustrated diagrammatically in FIG. 5, As disclosed therein, the three-position valve 74 can occupy a neutral position, in which fluid under pressure from the pump 71 flows through the pump discharge line 73 into the valve and then returns therefrom through the return line 75 to the supply tank 72. When in this position, fluid cannot flow through either of the other lines 79, 88 to either the head or rod ends of the lift cylinders 45 or to either the head or rod ends of the shock absorber cylinders 60. Actuation of the control liver 76 by the operator in on e direction, as upwardly as disclosed in FIG. 5, will place the high pressure pump discharge line 73 in communication with the

fluid lines

79, 80, 81, 82 running to the head ends 50 of the lift cylinders 45 and to the head ends 62 of the shock absorber cylinders 50, elevating the pistons 47 in the lift cylinders to elevate the entire grooving mechanism G from the pavement R, and at the same time shifting the pistons 63 in the shock absorber cylinders downwardly to lower the shock absorber wheels or rollers 70. Fluid in the rod ends 51 of the lift cylinders 45 and in the rod ends 65 of the shock absorber cylinders 60 can then return through the

return line

90, 91, 89. 88, 75, to the supply tank 72.

To effect engagement of the shock absorber A and saw blades 32 with the pavement, the control lever 76 is moved in the opposite direction, to lower the spool 78 of the three-position valve to it slower position as seen in FIG. 5, which will place place the high pressure pump discharge line 73 in communication with the

fluid lines

88, 89, 90, 91 running to the rod ends 51 of the lift cylinders 45 and to the rod ends 65 of the shock absorber cylinders 60. At the same time, the head ends 50 of the lift cylinders 45 and the head ends 62 of the shock absorber cylinders 60 are placed in communication with the return line 75 running to the supply tank 72. The pistons 47 in the lift cylinders are then lowered therewithin to shift the movable frame 20 downwardly, together with the shock absorber mechanism A, depth-of-cut rollers 35 and saw blades 32 carried thereby, the fluid pressure in the rod ends 65 of the shock absorber cylinders 60 tending to elevate the pistons 63 therein. However, the fluid in the head ends 62 of these cylinders can only flow outwardly therefrom at a relatively slow rate, since all of such fluid must pass through the choke orifices or metering devices 84 before flowing through the

lines

82, 80, 79, 75, back to the supply tank 72.

Fluid under pressure is permitted to flow into the rod ends 51 of the lift cylinders 45 until the shock absorber rollers 70 engage the pavement R, the lift cylinders then moving upwardly to raise the rear end of the chassis 11 and the rear wheels 14 from the pavement surface, so that a large portion of the weight of the vehicle and of the grooving unit G is then being borne by the wheels or rollers 70 of the shock absorber unit, When the rear wheels 14 are elevated from the pavement, which for example, may be a distance of about 2 inches thereabove, the control lever 76 may be manipulated to place the three-position valve 74 in the neutral position, thereby trapping fluid in the rod ends 51 of the lift cylinders and in the rods ends 65 of the shock absorber cylinders. How ever the weight of the rear portion of the vehicle is being imposed on the hydraulic fluid in the rod portions of the lift cylinders 45, which thereby maintains a high unit pressure of fluid in such cylinders 45, which thereby maintains a high unit pressure of fluid in such cylinders, this pressure being transmitted through the fluid lines 90, 91 running to the rod ends of the shock absorber cylinders 60. Thus, there is fluid pressure in the shock absorber cylinders elevating the pistons 63 therein, the rate of elevation being determined by the rate at which the liquid in the head ends 62 of these cylinders can flow through the choke orifices 84 into the

lines

82, 81 running to the head ends 50 of the lift cylinders 45. As fluid is forced out of the head ends 62 of the shock absorber cylinders, the rollers 70 and the supports 67 carrying them move upwardly about their pivot pins 68 to permit descent of the movable frame and engagement of the rotative saw blades 32 against the pavement, the saw blades rotating to cut grooves S therein to a depth determined by contact of the depth-ofcut rollers 35 with the pavement surface.

When the grooving unit is to be raised by the operator, the valve 74 is shifted to the upper position (Fig. 5), so that fluid under pressure flows into the head ends 50 of the lift cylinders 45 and also the head ends 62 of the shock absorber cylinders 60. The lift pistons 47 are thereby elevated to swing the arms 17 upwardly and lift the entire grooving unit G from the pavement, beginning the cutters 32 and depth-of-eut rollers 35 out of engagement therewith, as well as raising the shock absorber wheels 70, the fluid under pressure also being imposed through the lines 82 and past the check valve 85 into the head ends 62 of the shock absorber cylinders 60, to shift the pistons 63 and rods 64 downwardly and relocate the rollers 70 in their .lower position with respect to the movable frame 20. The

pistons and piston rods in the shock absorber cylinders are extended quite rapidly, since fluid under pressure can flow relatively freely past the check valves 85 and into the head ends of the cylinders, as distinguished from the relatively slow rate of flow of the fluid from the head ends 62 of the cylinders 60 through the choke orifices 84 when the pistons 63, rods 64 and the rollers 70 are to be elevated. During elevation of the lift pistons 47 and lowering of the shock absorber pistons 63, the oil from the rod sides of their companion cylinders flows through the

lines

90, 91, 88 and through the control valve 74 into the return line 75 that carries it back to the supply tank 72.

Following full elevation of the cutters of the grooving unit G, which will be first accompanied by reengagement of the rear wheels 14 with the pavement R, the valve 74 can be shifted to its neutral position, thereby trapping oil in the head ends 50 of the lift cylinders 45 and in the head ends 62 of the shock absorber cylinders 60, which will retain the grooving unit G in the elevated ed position, as well as the shock absorber rollers 70 in their maximum depending position with respect to the saw blades 32 and the depth-of-cut rollers 35. The weight of the grooving unit G and the swing arms 17 is large and is being imposed through the piston rods 48 and the pistons 47 on the liquid in the head ends 50 of the lift cylinders, such liquid under pressure also behind imposed through the fluid in the

lines

81, 82 on the liquid in the head ends 62 of the shock absorber cylinders 60, thereby insuring a large pressure holding the shock absorber rollers 70 in their lowermost position and capable of resisting upward movement relative to the movable frame 20 of the grooving unit G.

When the control valve 74 is manipulated to lower the grooving unit G into its working position, oil can flow from the head ends of the lift and shock absorber cylinders to the tank 72. However, the weight of the parts is still being imposed through the lift pistons 47 on the oil in the head ends 50 of the lift cylinders 45 and in the

lines

81, 82 connected thereto, the pressure of this oil also being present in the head ends 62 of the shock absorber cylinders to retain the pistons 63 and rot lers 70 in their lowermost or extended position, the oil in the

lines

81, 82 being at a relatively high pressure. The introduction of fluid under pressure into the rod ends 51 of the lift cylinders and into the rod ends 65 of the shock absorber cylinders will occur and will first contact the shock absorber rollers 70 with the pavement, the oil under pressure in the head ends 62 of the cylinders 60 still being at a high value and preventing retraction of the shock absorber pistons 63 upwardly in such cylinders until the rear wheels 14 are elevated from the pavement, the entire weight of the rear portion of the unit at first being borne by the shock absorber rollers 70. However, the saw blades 32 and depth-of-cut rollers 35 are still out of contact with the pavement. As an example, when the shock absorber wheels 14 first contact the pavement, the saw blades 32 may be located approximately 1% inches above the pavement R. Following contact of the wheels 70 with the pavement the fluid pressure in the rod ends 51,65 of the lift cylinders 45 and shock absorber cylinders 60 increases due to flow of oil from the pump 71 through the valve 74, such pressure increase also being imposed on the fluid in the rod ends of the shock absorber cylinders The fluid in the head ends 62 of the shock absorber cylinders is then forced by the upward movement of the pistons 63 out through the choke orifices 84 and back through the valve 74 and the return line 75 to the tank 72, such outward flow permitting upward retraction of the pistons 63 and rods 64 in the cylinders 60 and elevation of the shock rollers 70 to permit the gradual descent of the cutters 32 against and into the pavement to cut the grooves S therewithin, as limited by engagement of the dcpth-of-cut rollers 35 with the pavement. The upward retraction of the shock absorber rollers 72 and the descent of the cutters 32 and depth-of-cut rollers 35 occurs relatively slowly and at a uniform controlled velocity, giving the cutters an opportunity to cut into the concrete pavement to the desired depth, which, for example, may be one-sixteenth to one-eighteenth of an inch. The vehicle is then moved along the pavement by the power being transmitted from the engine 15 through the vehicle transmission to the front wheels 12, the rear wheels 14 merely rotating freely since they are elevated from contact with the pavement.

in the event that descent of the movable frame 20, as a result of introducing fluid under pressure into the rod ends 51 of the lift cylinders 45, occurred rapidly, the cutters 32 would be prevented from contacting or impacting against the pavement, since the shock absorber rollers 70 will first contact the latter. Even if the movable frame 20 were to drop for some reason, the shock absorber rollers 70 would first contact the pavement R and prevent the impacting of the cutters 32 against the pavement. As a result of elevation of the grooving unit G from the pavement, the fluid pressure automatically extends the shock absorber pistons 63 and rods 64 and their associated wheels 70, whereby they are in a position to initially reengage the pavement once more.

Iclaim:

1. ln a machine for performing a cutting action on a road way: a support movable generally vertically toward and from the roadway; cutter means carried by the support for cutting the roadway; means for moving said support and cutter means towards and from the roadway; and shock absorber means mounted on and carried by said support and movably vertically with respect thereto and engageable with the roadway prior to engagement of said cutter means with the roadway, said shock absorber means embodying means for retarding descent of said support toward the roadway and of said cutter means into engagement with the roadway after engagement of said shock absorber means with the roadway.

2. In a machine as defined in claim 1; and means responsive to operation of said moving means in elevating said support and cutter means for lowering said shock absorber means relative to said support and cutter means.

3. In a machine as defined in claim 1; and means responsive to operation of said moving means in lowering said support and cutter means for elevating said shock absorber means relative to said cutter means and support after engagement of said shock absorber means with the roadway.

4. in a machine as defined in claim 1; and instrumentalities responsive to operation of said moving means in elevating said support and cutter means for lowering said shock absorber means relative to said support and cutter means, said instrumentalities being responsive to operation of said moving means in lowering said support and cutter means for elevating said shock absorber means relative to said cutter means and support after an engagement of said shock absorber means with the roadway.

5. In a machine as defined in claim 1; said cutter means comprising a gang of retractable parallel saw blades for cutting a plurality of parallel grooves simultaneously in the roadway.

6. In a machine for performing a cutting action on a roadway: a support movable generally vertically toward and from the roadway; cutter means carried by said support for cutting the roadway; fluid operated means for moving said support and cutter means toward and from the roadway; fluid operated shock absorber means carried by said support and engageable with the roadway prior to engagement of said cutter means with the roadway for retarding descent of said cutter means into engagement with the roadway.

7. In a machine as defined in claim 6; and means for directing fluid under pressure simultaneously to said fluid operated means and fluid operated shock absorber means for elevating said support and cutter means and for lowering said shock absorber means relative to said cutter means.

8. In a machine as defined in claim 6; and means for directing fluid under pressure simultaneously to said fluid operated means fluid operated shock absorber means for lowering said support and cutter means and for elevating said shock absorber means relative to said cutter means after engagement of said shock absorber means with the roadway.

10. in a machine as defined in claim 6; and means for directing fluid under pressure simultaneously to said fluid operated means and fluid operated shock absorber means for elevating said support and cutter means and for lowering said shock absorber means relative to said cutter means; and means for directing fluid under pressure simultaneously to said fluid operated means and fluid operated shock absorber means for lowering said support and cutter means and for elevating said shock absorber means relative to said cutter means after engagement of said shock absorber means with the roadway.

10. In a machine as defined in claim 6; and means for directing fluid under pressure simultaneously to said fluid operated means and fluid operated shock absorber means for lowering said support and cutter means and for elevating said shock absorber means relative to said cutter means after engagement of said shock absorber means with the roadway; and flow restricting means in said fluid directing means for retarding elevation of said shock absorber means shock absorber means with the roadway.

11. In a machine as defined in claim 6; said cutter means comprising a gang of rotatable parallel saw blades for cutting a plurality of parallel grooves simultaneously in the roadway.

12. In a machine for performing a cutting action on a roadway: a vehicle adapted to traverse the roadway and having a first frame; a second frame movable generally vertically toward and from the roadway cutter means carried by said second frame for cutting the roadway; first cylinder means connected to one of said frames; first piston means slidable in said cylinder means and connected to the other of said frames; fluid operated shock absorber means carried by said second frame and comprising a roadway contacting member second cylinder means; one of said second cylinder means and second piston means being connected to said second frame, the other of said second cylinder means and second piston means being connected to said roadway contacting member; said second cylinder means having fluid therein acting upon said second cylinder means and second piston means whereby said roadway contacting member engages the roadway prior to engagement of said cutter means with the roadway for retarding descent of said cutter means into engagement with the roadway.

13. in a machine as defined in claim 12; and means for directing fluid under pressure to one portion of said first cylinder means and to one portion of said second cylinder means for elevating said second frame and cutter means and for lowering said roadway contacting member relative to said cutter means.

14. In a machine as defined in claim 12; and means for directing fluid under pressure simultaneously to one portion of said first cylinder means and to one portion of said second cylinder means for lowering said second frame and cutter means and for elevating said roadway contacting member contacting relative to said cutter means after engagement of said roadway contacting member with the roadway.

15. In a machine as defined in claim 12; and means for directing fluid under pressure to one portion of said first cylinder means and to one portion of said second cylinder means for elevating said second frame and cutter means and for elevating said second frame and cutter means and for lowering said roadway contacting member relative to said cutter means; and means for directing fluid under pressure simultaneously to another portion of said first cylinder means and to another portion of said second cylinder means for lowering said frame and cutter means and for elevating said roadway contacting member relative to said cutter means after engagement of said roadway contacting member with the roadway.

16. la a machine as defined in claim [2; and means for directing fluid under pressure simultaneously to one portion of said first cylinder means and to one portion of said second cylinder means for lowering said second frame and cutter means and for elevating said roadway contacting member relative to said cutter means after engagement of said roadway contacting member with the roadway; and flow restricting means in said fluid directing means for retarding elevation of said roadway contacting member relative to said cutter means after engagement of said roadway contacting member with the roadway.

17. In a machine as defined in claim 12, said cutter means comprising a gang of rotatable parallel saw blades for cutting a plurality of parallel grooves simultaneously in the roadway.

18. In a machine for cutting grooves in a set surface traversed by vehicles: a vehicle having a roadway engaging set of forward wheels and a roadway engaging set of rear wheels and including drive means for at least one of said sets of wheels; a frame connected to said vehicle and moving vertically with respect thereto; cutter means rotatably mounted on said frame; means for rotating said cutter means to cut grooves in the roadway surface; means operatively connected between said vehicle and frame for moving said frame vertically to selectively elevate said cutter means from the roadway surface or to shift said cutter means into engagement with the roadway surface and elevate a set of wheels from engagement with the roadway surface, whereby the weight of the frame and a portion of the weight of the vehicle are applied to said cutter means; said vehicle. frame and cutter means being moved along the roadway surface by said drive means rotating the set of wheels remaining in engagement with the roadway surface; and shock absorber means carried by said support and engageable with the roadway surface prior to engagement of said cutter means with the roadway surface for retarding descent of said cutter means into engagement with the roadway surface.

19. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slideable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface.

20. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and con nected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for elevating said frame and cutter means and for lowering said roadway surface engaging member relative to said cutter means.

21. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid cylinder and to one portion of said second cylinder for lowering said frame and cutter means and for elevating said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway.

22. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for elevating said frame and cutter means and for lowering said roadway surface engaging member relative to said cutter means; and means for directing fiuid under pressure simultaneously to an other portion of said first cylinder and to another portion of said second cylinder for lowering said frame and cutter means and for elevating said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface.

23. In a machine ad defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for elevating said frame and cutter means and for lowering said roadway surface engaging member relative to said cutter means; and means for directing fluid under pres sure simultaneously to another portion of said first cylinder and to another portion of said second cylinder for lowering said frame and cutter means and for elevating said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface; and flow restricting means in said firstmentioned fluid directing means for retarding elevation of said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface.

24. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber beans being mounted on said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and s second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for elevating said frame and cutter means and for lowering said roadway surface engaging member relative to said cutter means; and means for directing fluid under pressure simultaneously to another portion of said first cylinder and to another portion of said second cylinder for lowering said frame and cutter means and for elevating said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface; and flow restricting means in said firstmentioned fluid directing means for retarding elevation of said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface; said cutter means comprising a gang of rotatable parallel saw blades for cutting a plurality of parallel grooves simultaneously in the roadway surface.

UNITED STATES lA'lEN'i OFFICE CERTIFICATE OF CORREC'IION Patent No. r3,608,969 Dated September 28, 1971 1 v t JOSEPH s. FOWKES It is certified that error appears in the above identificd parent and that said Letters Patent are hereby corrected as shown below:

r Column- 6 line. 67 (claim 1, line 16) "movably" should be --movab1e--.

Column 7, line 20, cancel "retractable" and substitute --rotatabl-e--; line 39 (claim, 8, line 3), before "fluid" insert --and-- line 43-, the number of the claim designated "10" should be --9:'-; line 60 (claim 10, line 8) after "means" first occurrence) insert --relative to said cutter means a ter engagement of said; line 68 (claim 12, line 4) after "roadway insert a line 73 (claim 12, line 9), before "second" insert a Column 8, line 1, after "means" (first occurrence) insert and second piston means slidable in said second cylinder, means--; lines 21 and 22 (claim 14, lines 5 and 6), cancel "contacting"; lines 27 and 28 (claim 15, lines 4 and 5) cancel "and for "elevating said second frame and cutter means"; line 51 (claim 18, line 1) "set" should be --roadway-.

Column 9, line 39 (claim 21, line 12) after "fluid" insert --under pressure simultaneously to one position of said first-;; line 60 (claim 22, line 17) "an other" should be --anot er--. c

Column 10, lines 35 and 3b, cancel "said shock absorber beans being mounted on said frame;"; line 39, "a" should be Signed and sealed this 21st day of March 1972.

(SEAL) Attest z EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims

1. In a machine for performing a cutting action on a roadway: a support movable generally vertically toward and from the roadway; cutter means carried by the support for cutting the roadway; means for moving said support and cutter means towards and from the roadway; and shock absorber means mounted on and carried by said support and movable vertically with respect thereto and engageable with the roadway prior to engagement of said cutter means with the roadway, said shock absorber means embodying means for retarding descent of said support toward the roadway and of said cutter means into engagement with the roadway after engagement of said shock absorber means with the roadway.

4. In a machine as defined in claim 1; and instrumentalities responsive to operation of said moving means in elevating said support and cutter means for lowering said shock absorber means relative to said support and cutter means, said instrumentalities being responsive to operation of said moving means in lowering said support and cutter means for elevating said shock absorber means relative to said cutter means and support after engagemenT of said shock absorber means with the roadway.

5. In a machine as defined in claim 1; said cutter means comprising a gang of rotatable parallel saw blades for cutting a plurality of parallel grooves simultaneously in the roadway.

9. In a machine as defined in claim 6; and means for directing fluid under pressure simultaneously to said fluid operated means and fluid operated shock absorber means for elevating said support and cutter means and for lowering said shock absorber means relative to said cutter means; and means for directing fluid under pressure simultaneously to said fluid operated means and fluid operated shock absorber means for lowering said support and cutter means and for elevating said shock absorber means relative to said cutter means after engagement of said shock absorber means with the roadway.

10. In a machine as defined in claim 6; and means for directing fluid under pressure simultaneously to said fluid operated means and fluid operated shock absorber means for lowering said support and cutter means and for elevating said shock absorber means relative to said cutter means after engagement of said shock absorber means with the roadway; and flow restricting means in said fluid directing means for retarding elevation of said shock absorber means relative to said cutter means after engagement of said shock absorber means with the roadway.

12. In a machine for performing a cutting action on a roadway: a vehicle adapted to traverse the roadway and having a first frame; a second frame movable generally vertically toward and from the roadway; cutter means carried by said second frame for cutting the roadway; first cylinder means connected to one of said frames; first piston means slidable in said cylinder means and connected to the other of said frames; fluid operated shock absorber means carried by said second frame and comprising a roadway contacting member, second cylinder means, and second piston means slidable in said second cylinder means; one of said second cylinder means and second piston means being connected to said second frame, the other of said second cylinder means and second piston means being connected to said roadway contacting member; said second cylinder means having fluid therein acting upon said second cylinder means and second piston means whereby said roadway contacting member engages the roadway prior to engagement of said cutter means with the roadway for retarding descent of said cutter means into engagement with the roadway.

15. In a machine as defined in claim 12; and means for directing fluid under pressure to one portion of said first cylinder means and to one portion of said second cylinder means for elevating said second frame and cutter means and for lowering said roadway contacting member relative to said cutter means; and means for directing fluid under pressure simultaneously to another portion of said first cylinder means and to another portion of said second cylinder means for lowering said frame and cutter means and for elevating said roadway contacting member relative to said cutter means after engagement of said roadway contacting member with the roadway.

16. In a machine as defined in claim 12; and means for directing fluid under pressure simultaneously to one portion of said first cylinder means and to one portion of said second cylinder means for lowering said second frame and cutter means and for elevating said roadway contacting member relative to said cutter means after engagement of said roadway contacting member with the roadway; and flow restricting means in said fluid directing means for retarding elevation of said roadway contacting member relative to said cutter means after engagement of said roadway contacting member with the roadway.

18. In a machine for cutting grooves in a roadway surface traversed by vehicles: a vehicle having a roadway engaging set of forward wheels and a roadway engaging set of rear wheels and including drive means for at least one of said sets of wheels; a frame connected to said vehicle and moving vertically with respect thereto; cutter means rotatably mounted on said frame; means for rotating said cutter means to cut grooves in the roadway surface; means operatively connected between said vehicle and frame for moving said frame vertically to selectively elevate said cutter means from the roadway surface or to shift said cutter means into engagement with the roadway surface and elevate a set of wheels from engagement with the roadway surface, whereby the weight of the frame and a portion of the weight of the vehicle are applied to said cutter means; said vehicle, frame and cutter means being moved along the roadway surface by said drive means rotating the set of wheels remaining in engagement with the roadway surface; and shock absorber means carried by said support and engageable with the roadway surface prior to engagement of said cutter means with the roadway surface for retarding descent of said cutter means into engagement with the roadway surface.

20. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for elevating said frame and cutter means and for lowering said roadway surface engaging member relative to said cutter means.

21. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for lowering said frame and cutter means and for elevating said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway.

22. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for elevating said frame and cutter means and for lowering said roadway surface engaging member relative to said cutter means; and means for directing fluid under pressure simultaneously to another portion of said first cylinder and to another portion of said second cylinder for lowering said frame and cutter means and for elevating said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface.

23. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for elevating said frame and cutter means and for lowering said roadway surface engaging member relative to said cutter means; and means for directing fluid under pressure simultaneously to another portiOn of said first cylinder and to another portion of said second cylinder for lowering said frame and cutter means and for elevating said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface; and flow restricting means in said first-mentioned fluid directing means for retarding elevation of said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface.

24. In a machine as defined in claim 18; said means for moving said frame comprising a first cylinder connected to said vehicle, a first piston slidable in said first cylinder and connected to said frame; said shock absorber means being mounted on said frame and including a roadway surface engaging member, a second cylinder connected to said frame, and a second piston slidable in said second cylinder and connected to said roadway surface engaging member; said second cylinder having fluid therein exerting pressure between said second cylinder and second piston to retard descent of said cutter means into engagement with the roadway surface; and means for directing fluid under pressure simultaneously to one portion of said first cylinder and to one portion of said second cylinder for elevating said frame and cutter means and for lowering said roadway surface engaging member relative to said cutter means; and means for directing fluid under pressure simultaneously to another portion of said first cylinder and to another portion of said second cylinder for lowering said frame and cutter means and for elevating said roadway surface engaging member with the roadway surface; and flow restricting means in said first-mentioned fluid directing means for retarding elevation of said roadway surface engaging member relative to said cutter means after engagement of said roadway surface engaging member with the roadway surface; said cutter means comprising a gang of rotatable parallel saw blades for cutting a plurality of parallel grooves simultaneously in the roadway surface.