US2658408A - Electrical control means for change-speed gearing - Google Patents

Description

Nov. 10, 1953 ELECTRICAL CONTROL MEANS FOR CHANGE-SPEED GEARING Filed May 51. 1951 I A. A. MILLER 2,658,408

4 Sheets-Sheet l m wk In v (En-bOD Nov. 10, 1953 MILLER 2,658,408

ELECTRICAL CONTROL MEANS FOR CHANGE-SPEED GEARING Filed May 51, 1951 4 Sheets-Sheet 2 ezvboz izwijyzzaz z Nov. 10, 1953 A. A. MlLLER 2,658,408

ELECTRICAL CONTROL MEANS FOR CHANGE-SPEED GEARING Filed May 31, 1951 I 4 Sheets-Sheet 5 ,zliwezvtol Lien Nov. 10, 1953 A. A. MILLER 2,658,408

ELECTRICAL CONTROL MEANS FOR CHANGE-SPEED GEARING Filed May 51, 1951 4 Sheets-Sheet 4 Patented Nov. id, i953 UNIT.

ELECTRICAL CQNERQL MEANS FOR CHANGE-SPEED GEARING Application May 31, 1951, Serial No. 229,114

@laims priority, application Great Britain June 5, 1950 21 Claims.

This invention relates to electrical control means for change speed gearing of the kind comprising electrical circuits controlled by contact members or switches and means controlled or actuated by said circuits for automatically effecting the engagement of either a higher or a lower gear in accordance with the closing or open ng of one or other of said circuits. She invention may be applied with particular advantage to arrangements of the above kind including electrical contact members movable relatively in two directions, movement in one direction being 111 accordance with the speed of a part of the tra mission and movement in another tion being in accordance with the fuel sup ply or throttle opening or" an internal combustion prime mover, as described for example in British patent specification No. 457,269. invention may be applied. to gearing provided with any convenient means for eiiecting the changes in gear ratio, such for example as fluid actuated devices controlled by electro-magnetically operated valves, and such devices may be employed to actuate the brakes of epicyclic gears affording the required ratios, although the mvention is not restricted to the use of such actuating means.

It is an object of the invention to provide control means of the above kind which can addition be manually controlled by selecting and engaging any desired gear irrespective of the particular gear engaged.

A further object of the invention is to enable control means of the above kind having automatic control in accordance with speed and fuel supply or throttle opening conditions of a prime mover to be manually instead of automatically controlled when required so that a desired gear ratio can be maintained irrespective of the aforesaid conditions, and to provide convenient and easily operable means for achieving this result. A further object is to provide alternative manual and automatic control means which may be exchanged with saiety at any time while the transmission is in motion without risk of over-speeding the prime mover, such as might occur 1:" on changing from manual to automatic control an inappropriate change to lower gear were produced. A further object is to provide an proved construction of manually operable switch for the above purposes. A further object is to provide an improved construction of governor actuated electrical contact members.

The invention consists in electrical control means for change speed gearing comprising elecn t t adam -1 e-cg afi a; E Ai this i hai it (Cl. Wi -472) trical circuits controlled by contact members or switches, means controlled or actuated by said circuits for automatically effecting the engagernent of either a higher or a lower gear in accor-dance with the closing or opening of one or other of said circuits, and manually operable selection switch means for interrupting said circuits and for selectively closing other circuits including electrical means for controlling engagement of diiierent gear ratios, the arrangement being such that gear changing is effected either by the first said circuits or by the second said circuits according to the position of the selection switch means.

The invention also consists in electrical control means for change speed gearing comprising electrical contact members movable relatively in two directions, movement in one direction being in accordance with the speed of a prime mover or transmission part and movement in another direction being in accordance with the fuel supply or throttle opening of the prime mover, electrical circuits controlled by said contact members, means controlled by said circuits for automatically selecting and engaging different gear ratios in accordance with speed and fuel supply or throttle opening conditions, and manually operable selection switch means for interrupting said circuits and-for selectively closing other circuits including electrical means for controlling engagement of the difierent gear ratios, the arrangement being such that gear changing is either automatic or manually controllable according to the position of said selection switch means.

The invention also comprises an arrangement according to either of the two preceding paragraphs in which the first mentioned contact members or switches control the circuits of relays for eifecting operation of a selection switch, through ratchet or other means in one or other direction to close circuits for actuating different gear ratio engagement means, said relays being provided with time delay means, for example a shunt connected condenser or an additional short-circuited winding or induction sleeve so that they cannot operate successively within a predetermined peiod. lj'he engagement of the selected gears is effected through the medium of electro-magnetic devices which are preferably energised by relays, thereby reducing the current to be carried by the contacts of the selection switch. These relays are also preferably provided with time delay means.

According to a further feature of the invention, the manually operable selection switch is provided with a contact or contacts arranged to be automatically gaged each time the switch is operated to change the gear ratio, such engagement causing the closing of a circuit associated with the automatic selection switch to ensure the positioning of the latter in an intermediate gear position and thereby obviate inappropriate gear changes.

A current economising resistance may be included in the circuits of the gear engaging control devices, and means may be associated with the automatic and manual control circuits for short-circuiting said resistance at each gear changing operation. Thus in a preferred arrangement, means is provided for locking the operating handle of the manually operable selection switch in the selected positions, and the motion required to unlock the handle causes contact means to become operative and to effect the closing of a circuit or circuits when the handle is moved to another position and thereby short-circuit the resistance.

In the accompanying drawings,

Figure 1 is a diagram showing the connections of an electrical control means for change speed gearing arranged in accordance with the invention;

Figure 2 is a sectional elevation, with certain details omitted, of the brake actuating and control mechanism for an epicyclic gear box for use in conjunction with control means according to the invention;

Figure 3 is a sectional elevation of a manual selection switch constructed and arranged in ac cordance withthe invention;

Figure 4 is an end elevation of the selection switch as viewed in the direction of the arrow A in Figure 3;

Figure 5 is a sectional elevation, taken on the line 5-5 of Figure 6, of a governor and throttle control mechanism constructed and arranged in accordance with the invention;

Figure 6 is a cross section of the mechanism of Figure 5;

Figure '7 is a section taken on the line 1-7 of Figure 6 Figure 8 is a diagram showing the connections of a modified form of electrical control means.

In carrying the invention into efiect according to one convenient mode, the connections for a control arrangement intended to be applied to an epicyclic gear box aifording four forward gear ratios and reverse is shown in Figure 1. A governor actuated electrical contact arrangement is provided comprising a movable contact member I connected to a speed governor and displaceable in relation to a pair of shaped contact surfaces 2 and 3 which are themselves movable in a different direction in accordance with the fuel supply and throttle opening as described in British patent specification No. 457,269. The contact surface 2 is connected to the coil 4 of a change-up relay having a movable armature 5 controlling contacts 6 and 'I. The contact surface 3 is connected to the coil 8 of a change-down relay having movable armatures 9 and Id. The armature 9 controls contacts H and I2 and the armature Ill controls back contacts 13 and I l. The contacts 6 and l of the change-up relay control the circuit of an electromagnet [5 having an armature It for actuating a ratchet'pawl ll loaded by a spring IS. The contacts H and I2 of the change-down relay control the circuit of an electromagnet l9 having an armature for actuat- 4 ing a ratchet pawl 2| loaded by a spring 22. The ratchet pawls I1 and 2| are arranged so that when operated they engage a ratchet wheel 23 to which is connected the contact arm of an automatic selection switch. This arm is not shown in Figure 1, but it carries four contact strips 24, 25, 26 and 27. Operation of the ratchets causes step by step displacement of the ratchet wheel 23 in one or other direction according to which ratchet is operated. The movable contact member l of the speed governor is connected through a resistance 28 and pairs of contacts 29 and 30, which are broken when the ratchets are operating, to one of a pair of contacts on a manual selection switch to be described hereinafter, which contacts are bridged when the said switch is in position for automatic operation, and the second of said contacts is connected to the positive side of the electrical supply which may conveniently comprise a battery. Thus the aforesaid relays can be energised through the governor actuated contacts I and 2 or I and 3 only when the manual selection switch occupies an appropriate position.

The relay coil 4 is connected to a series of contacts 3| on the automatic selection switch which can be connected by the switch strip 24 to contacts 32 which are connected to the negative side of the supply battery 33. Similarly the relay coil 8 is connected to a series of contacts 34 which can also be connected by the switch contact strip 24 to the negative side of the supply. The switch arm has four positions corresponding to first, second, third and fourth speeds, the reverse being obtained by manual control only. In Figure 1 the lowest radial line of contacts occupied by the switch contact strips 24, 25, 26 and 2? corresponds to first speed, the line of contacts above it to second speed, the line above that to third speed and the upper line to 'fourth speed. It will be seen that the series of contacts Si, 32 and 34 are so arranged that in each end or limit position of the switch arm the circuit of one of the relay coils 4 or 8 is interrupted. The arrangement is such that if the automatic selection switch is in a position corresponding to second speed for example, and the engine speed rises to a predetermined value, the governor actuated contact member I will move to close the circuit of the change-up relay 4 which causes actuation of the magnet 15 and ratchet H to move the automatic selection switch arm to the next position corresponding to third speed. If, however, the switch arm is already in fourth speed position, there is no contact of the series 3| connected to the relay coil 4 and hence the relay cannot beenergised. The same considerations apply when changing down, since the lowest contact of the series 34 has no connection with the relay coil 8. The relay coils 4 and 8 are shunted by condensers 35 and 36 so that a time lag of a few seconds is introduced which prevents successive operations within a shorter time interval.

The contact strip 25 of the ratchet switch arm controls series of contacts 31 and 38. The contacts 31 are connected through the manual selection switch to the positive side of the battery 33, this connection being made only when the said switch is in position for automatic operation as will be described hereinafter. The contacts of series 38 are connected respectively to the coils 39, 40 and Al of three valve controlling relays corresponding to first, second and third speeds. These ralays are preferably equipped with induction sleeves to provide a time delay in their operation. The relay coil 39 can actuate a movable contact 42 to make with a fixed contact l? connected to an electromagnet Ml to bring in the first speed gear as hereinafter described. The movable contact 42 also has a back contact 35 which is connected to the back contact i l of the change-down relay 8. The movable contact 46 of the relay M3 is arranged to make with a fixed contact All connected to an electromagnet i8 for bringing in the second speed gear. The movable contact 46 also has a back contact 49 and is connected to the back contact 15. The back contact 89 is connected to the back contact iii of the change-down relay 8. The relay ll has a movable contact 50 connected to the back contact 39 of relay 40 and is arranged to make with a fixed contact 5! which is connected to an electro-magnet 52 for bringing in the third speed. The movable contact 50 is also connected to a contact 53 in the automatic selection switch. When the switch arm is in fourth speed position, this contact 53 is connected by the contact strip El to a contact 5E which is itself connected to an electromagnet 55 for bringing in the fourth speed, this being effected, it will be noted, without the intervention of a relay.

The contact strip 25 of the ratchet switch controls a series of pairs of contacts ee, 57!; 5t, 59; and til, 69 which correspond to first, second and fourth speeds respectively. The contacts E-ii, 58 and (it are connected together and to an appropriate contact in the manual selection switch. The contacts 5? and 59 are connected through a resistance $2 to the end I33 of change-up relay coil 4. The contact BI is connected to the coil of the change-down rela 8. A fifth electro-magnet coil 63 is provided for bringing in the reverse gear. All the electro-magnet coils are connected on one side to the negative side of the battery 33. The electro-magnet coils it, d3, 52 and 5'5 are connected on the other side through the m terconnected relay contacts and an economising resistance 65 to the positive supply through appropriate contacts in the manual selection switch. The contacts 1 and E2 on the changeup and change-down relays 4 and 8 are arranged to short-circuit the resistance 65 when either one of the relays is energised so that the current in the selected solenoid coil is a maximum at this time. As soon as the relay has caused operation of the appropriate ratchet, the contacts 29 or as on the ratchet are broken so that the relay is de-energised after the previously mentioned time delay and the resistance 65 is re-introduced into the selected electromagnet circuit, thereby diminishing the current flowing.

It will be understood that the electro-inagnets previously referred to are arranged to operate hydraulic or pneumatic valves controlling hydraulic or pneumatic pistons for applying the brakes and/or clutches to epicyclic gears and thereby engaging the corresponding gear ratio of the gear box. A convenient arrangement for this purpose is illustrated in Figure 2. A gear box indicated generally at 665 is of the usual epicyclic type and has a brake drum (not shown) with brake band t8 and line 61, one end of which is anchored by a link $9. The other end of the brake band is connected to a link if! having a head "ll bearing on a lever l2 fulcrumed at 13 on the link 69 and bearing at its other end on a bell crank is pivoted at and connected by a rod '66 to a pneumatic piston "H. Air from a supply pipe i8 is admitted to the operating cylinder is under the control of a spring loaded valve an connected by a spindle 8| to an armature 82 arranged to be actuated by the electro-magnet coil 83 to open the valve 80. An exhaust outlet 8 is controlled by a valve member 85. An arrangement of this kind is employed for bringing in the four forward speeds and the reverse gear.

The manually operable selection switch is shown in Figures 3 and i and the contact arrangement is shown in Figure 1. The movable part of the switch comprises four contact or brush arms 36, 3?, 88 and 89, two of which are shown in Figure 3. These arms are in electrical connection and are arranged in the form of a cross upon a plate as which is supported by means of a central recess s1 upon a central pivot 82 which is vertically movable against a loading spring 93. A handle 9G is located upon the plate 98 and is secured thereon by an upper plate at rotatably seated in a central sleeve 96 in the switch casing 9'5 and connected to the lower plate fit. Springs 98 are interposed between the upper plate and the handle body, and the latter is also connected by horizontal pivots 98a to side plates as of the upper plate 95. A pin mil in the upper plate $5 is engageable in any one of a series of indexing recesse in a member is! secured to the casing 9?. The handle lid projects laterally through an opening in the casing wall, which opening is of gate form as shown in Figure i and comprises spaced parallel slots see and 583 connected intermediately by a short vertical slot ta l. The upper slot 102 has markings 3 and 4 indicating third and fourth speeds. Instead of 4 the marking A may be employed to indicate automatic control. The lower slot its is marked R, 1 and 2 for reverse, first and second speeds. A spring loaded pin is mounted in the casing to prevent inadvertent movement of the handle to reverse position. The arrangement is such that the handle at can be rocked about its pivot pins 98a for passing through the gate slot Hi4 and can be moved laterally in either of the slots [02, I03 and indexed in the marked positions. A rod IDS is slidable longitudinally in the handle and is displaceable by a button it? in the handle end. The rod I35 engages a double conical or equivalent cam-shaped member Hi8 located in an enlarged bore in the handle body and loaded by a spring ice. The member its is engaged by a ball [it located in an aperture in the handle body wall, the ball being engaged by a pin III engaging a second ball H2 located within the sleeve 98. A screw M3 on the casing 9'! abuts the ball H2. This ball and pin arrangement is aligned with the spring loaded supporting pivot 92. The arrangement is such that pressure on the handle button it? displaces the cone member liltand thereby forces the contact plate 99 downwardly by depressing its supporting pivot s2. This motion also brings with it the upper plate 95 and releases the pin 59%] from the indexing recesses in the member It'll, thus enabling the contact plate to be angularly adjusted to another position. Four groups of contact studs are arranged beneath the contact arms, and two of these studs are shown at I M in Figure 3.

Referring to Figure 1, three contact studs H5, H8 and Ill comprise one group and are disposed at a level such that they will only be contacted by the arm 3? when the handle 94 is in the upper slot H325 of the gate, this being determined by the corresponding inclination of the contact arm plate lit. The stud H5 is a fourth Speed or automatic control stud and is connected by a line IIS through the contacts 29 and 30 to the governor controlled contact member 1. The stud H6 is a neutral stud and is connected to the third speed stud Ill and thence by a line II9 to the positive side of the third speed electro-magnet 52. A second group of four studs comprises a neutral stud I2I which is connected by a line I24 to the contacts 55, 58 and 60 of the automatic selection switch which are only contacted by the strip 26 when the arm is in first, second, or fourth speed positions. This neutral stud I2I is contacted by the arm 89 when the neutral stud H5 is contacted by the arm 81. The studs I26], I22 and I23 are all connected to the contact arms 5, 9 and IQ of the change-up and change-down relays. This second group of contacts are engageable by the contact arm 89 in either the upper or lower slot position of the handle 94. A third group of contacts comprises four studs I25, I26, I27 and I28 all connected to the positive side of the supply battery 33 and the economising resistance 65. These studs are arranged so that they are only engaged by their contact arm 88 when the button IIJ'I of the handle is depressed as is necessary when changing the handle position, and when contacted they short-circuit the resistance 65 when the circuit of the selected electro-magnet is closed, the resistance being re-introduced when the button is released. A fourth group of contacts comprises contact studs I29, IEG, I3I and I32 which are arranged so that they are only engaged when the handle at occupies the lower slot. The end or reverse stud 213 is connected to the positive side of the reverse gear electro-magnet 63. The first speed stud IE3 is connected to the positive side of the first gear electro-magnet 4G. The neutral stud I3I is connected to the end stud I32 and to the positive side of the second speed solenoid 4B. Thus when the arm 86 contacts with the appropriate stud of the fourth contact group, the circuit of either the reverse, first or second speed electromagnet will be completed through the corresponding stud of the second group (I20, I22 or I23) which is connected through the resistance 65 to the positive side of the battery 33. The arrangement is such that when the switch handle 94 is moved to fourth speed or automatic control position, automatic control is afforded from first to fourth speeds. Movement of the switch handle to reverse, first, second or third speed positions interrupts the automatic control circuits and closes the electro-magnet circuit of the selected gear to engage the same, the economising resistance 65 being short-circuited by contacting of the studs I25, I25, I27 or I28 as long as the handle button IE2? is depressed. Also the contacts of the groups are so arranged that a neutral contact is made when moving the handle through the gate from any one of the positions 1, 2, 3 or 4 (A) to any other of said positions.

It will be seen that with the manual selection switch in neutral position there is no electrical connection to the contact I I5 which is connected to the governor member I, nor is there any electrical connection to contacts I39, I32, II? or I29 because the arm 38 does not make with any of the supply contacts I25, I25, I2? or I23 unless the button of the switch handle is depressed, and the contact arm 89 lies on a contact I2I which is not connected to the supply. Thus none of the electro-magnets is energised and no gear is engaged,

It is not possible to move the switch arm 94 without first pressing the button I01, and this action causes the arm 88 to engage contact group I25, I26, I27, I28. Thus when the switch arm is moved to any one of the positions R, 1, 2 or 3, the four contact arms are electrically connected to the positive side of the battery and the arm 86 or 87 will carry the connection to the appropriate contact and current fiows directly to the appropriate electro-magnet winding, the circuit of which is completed through the common connection to the negative side of the bat tery. When the button I6? is released in the selected gear position the direct connection with the battery is interrupted by disengagement of the arm 88 with its group of contacts, but a reduced current is maintained through the arm 89 which is then engaged with one of the contacts I26, I22 or I23 which are connected through the economising resistance to the positive side of the battery. Thus having first applied the full battery voltage to the appropriate electro-magnet to ensure its positive actuation, a reduced current is then maintained to hold the magnet in it actuated position. This enables a relatively small magnet to be used without overheating when energised for long periods.

It is desirable that during manual control of the gear box as described above, the ratchet switch for automatic selection should be in third gear position, order that when it is brought into eiiect by reverting to automatic control it will not immediately actuate a gear ratio which might be too low or too high for the speed of the vehicle at the time of gear change. If the ratchet switch should be in first or second speed position when the automatic control is discontinued by moving the manual selection switch to a selected position the switch arm will of necessity be moved through the neutral position with the button I Eil depressed. This will complete a connection from the positive side of the battery through contact I27, arm 88, arm 39, contact I2I, and contact strip 26 on ratchet switch arm to the end 53a 01' the winding of the change-up relay, and thence through contact strip 24 of the ratchet switch and contacts 32 to the negative side of the battery. The changeup relay 4 is thus energised to complete a circuit from the positive side of the battery through relay contacts '5, contact arm 5 and contact 6 to magnet winding I5 and thence to the negative side of the battery. The magnet i5 is thus energised and moves the ratchet switch one step in a change-up direction, for example from first speed to second speed position. The next operation of the manual selection switch through the neutral position will repeat the energising of the change-up relay t and move the ratchet switch to third speed position. Further movement of the manual selection switch can have no effect upon the change up relay since the contact strip 25 on the switch arm will not make the necessary contact.

If the ratchet switch had been in fourth speed position when automatic control was discontinued, the ensuing movements of the manual switch arm 94 would complete a circuit through the ratchet switch contact strip 25 and contact SI to the end I 34 of the change-down relay coil 8, and thence through the coil to contact 34, through contact strip 24 to contacts 32, and thence to the negative side of the battery. Op-

eration of the change-down relay 8 which ensues will complete a circuit from the positive side of the battery through relay contacts H and i2 and contact arm 9 to the magnet winding it and thence to the negative side of the battery. The operation of the magnet is will then move the ratchet switch one step to third speed position.

Considering now the functioning or the automatic control, let it be assumed that the ratchet switch is in third speed position when the manual selection switch is moved to position 4 or A. This completes a circuit from the positive side of the battery through contact I28, arm til, contact M5, line H8, line I55, ratchet contact strip 2%, contact 38, relay winding M and thence to the negative side of the battery. The relay is thereby energised to complete a secondary circuit from the positive side of the battery through contact lZB, arm 88, arm 89, contact 28, line ltd, contact arm it, contact it (or alternatively line l3l, contacts 42, 45, G6, 49), contacts to and H of third speed magnet relay and through magnets 52 to the negative side of the battery, thereby engaging the third speed. When the button Hill is released by the operator, the circuit from the battery is completed through the resistance 55 as previously explained. If the vehicle is stationary when the automatic control is selected, or if for any other reason the engine speed is low enough to close the change-down contacts l, 3 in the governor switch, current will now from the positive side of the battery to the resistance 55 (the handle button till being assumed released) to contact I203, arm 89, arm contact 5525, contacts 3i] and 29, governor contact arm l, governor contact 3, the change-down relay coil 8, contacts 34, contact strip 24, contacts 32, and thence to the negative side of the battery. The changedown relay 3 is thereby energised and the condenser 35 is charged, the relay in turn closing and completing a circuit from the positive side of the battery through the relay contact 52, contact arm a, contact H, magnet coil is and thence to the battery negative, thereby operating the ratchet switch to move its arm one step down to I second speed position, thereby transferring the circuit from the third speed relay winding ll to the second speed relay winding as. The contacts of the second speed relay to will thereby be closed to complete a circuit from the positive side of the P battery through the change-down relay contact l2 and contact arm 9, line ltd, line 93?, relay contacts 42 and 35, relay contacts it and ll, the second speed magnet winding (it and thence to the negative side of the battery. When the contacts db and 5'? are closed, the contacts tit and 59 are opened. Simultaneously with the closing of the change-down relay contacts 82, H and 9, the back contacts is and is are opened, thereby interrupting the circuit of the third speed magnet relay contacts 5d and 5E, so that while the induction sleeve provided on the winding of the third speed rela winding il retains its contacts til, Si in closed condition for the required period for a changing-up operation (about second), the circuit supplying these contacts is instantaneously broken by the aforesaid back contacts it, it of the change-down relay, and the lag which is inherent in the action of the relay is prevented from being effective in the third speed magnet winding 52 which it has been controlling. The operation of the ratchet switch causing the change-down operation to take place has previously opened the contacts as and interrupted the circuit to the governor switch contacts i and 3 and the changedown relay coil 8 and its condenser so that the latter commence to discharge through its relay coil and holds the relay closed for a predetermined period (about two seconds). When this relay opens the circuit to the change-down magnet 353, the ratchet contacts 3d will be closed and the governor switch member i will again be connected to the positive side or" the battery and is ready for a further operation should the engine speed and throttle position be such as to close its contacts. A manual switch its is provided and connected to the contact 53% which is similar to contacts but occupies the second speed position of the ratchet switch contact strip When the manual switch is opened, the circuit through the change-down relay 8 will be broken when the ratchet switch arm reaches the second speed position and a further change-down cannot then occur.

If the engine speed rises sufliciently to close the governor switch contacts and 2, a circuit is completed from the positive side of the battery through the economising resistance the contact 52d of the manual selection switch, the switch arms as and ill, the contact H5, contacts iii and governor switch arm i, governor switch contact 2, the change-up relay winding t and its condenser 85, the contacts it, the ratchet arm contact strip 25., the contacts 32 and thence to the negative side of the battery. The consequent operation of the change-up relay closes a circuit from. the positive side or" the battery through the change-up relay contacts 1, ii and 6 through the magnet coil E5 to the negative side of the battery. The ratchet switch is thereby moved up one step, for example from second to third position. The movement of the ratchet arm contact strip transfers the supply from the relay coil at to the relay coil ll. The relay contacts l-5, fill remain closed for about half a second, maintaining the circuit through the second speed magnet 48 for this period after the actuation of the third speed magnet 52. It is to be noted that the circuit which supplies the relay contacts 56, 5| is not interrupted when changing-up as it is when changing-down. The operation of the ratchet switch when changing-up opens the contacts 294 and thereby interrupts the circuit to the governor switch arm l and thence through the contact 2 and the change-up relay l and its condenser 35. The condenser then commences to discharge through the relay winding it and maintains the relay contacts closed for approximately two seconds. During this period the aforesaid contacts 29 remain open and render the governor switch inoperative. This provides sufiicient time for the engine speed to accommodate itself to the new gear ratio before the governor switch becomes operative again. When the next upward change to fourth speed takes place, the ratchet switch contact strip 25 interrupts the circuit of the third speed relay coil All and the ratchet switch contact strip 27! occupies a position bridging the contacts 53 and 5t, thereby closing a circuit from the positive side of the battery through the change-up relay contacts l and 5, the line 36, the back contacts is and Hi of the change-down relay, the contacts 53 and a l previously men tioned, the fourth speed magnet 55, and thence to the battery negative. In the fourth speed position of the ratchet switch the contact strip 24 interrupts the circuit of the change-up relay winding fl and no further change in the upward direction of the switch can take place.

It is to be noted that the main purpose of the magnet relays 39, 44, 4! is to provide a slight pping of the magnet operations when changing-up as distinct from changing-down. For this reason the fourth speed magnet is not provided with a relay since no higher speed is provided. If the relays are needed to relieve the ratchet switch of heavy current, then a simple relay without an induction sleeve could be provided for the fourth speed magnet, its contacts replacing the existing contacts 55, 54 of the ratchet switch and its winding being connected between the ratchet switch arm contact corresponding to contact 38 but in fourth speed position, and the battery negative.

It will be seen that the back contacts 45 and 49 of the first and second speed magnet relays are employed to provide a supply circuit from the line 53f through each relay to the next higher speed relay so that when changing-down, the incoming relay isolates the next higher speed relay so as to prevent its lag factor from being effective when changing-down. When changingup, however, the incoming relay has an independent supply provided by the back contacts I3 and I4 on the change-down relay, as the outgoing relay remains closed for about half a second and is therefore unable immediately to supply the next higher speed relay through its back contacts.

The contact members I, 2 and 3 which are moved in accordance with speed and fuel or throttle conditions to effect automatic gear changing may be arranged as described in British patent specification No. 457,269, but preferably the construction shown in Figures 5, 6 and 7 is employed. This comprises a casing I45 in which is rotatably supported a shaft I4I carrying a pulley I42 which is driven from the engine. The governor actuated member I43 is of generally V shape carrying a V-shaped spring 44 on which are mounted a pair of contact studs I45, and is mounted on a spindle I46 for angular motion. A second rotatable spindle I41 carries a pair of contoured contact plates I48 secured to an insulating base I 49 and arranged between the aforesaid contact studs I45 which are in electrical connection. The spindle I4! has an arm I 55 which can be actuated from the throttle control of the internal combustion prime mover, the arrangement being such that at different angular positions of the spindle I41, the contact surfaces of the contoured plates I48 are at different distances from the contact studs I45. The speed governor is of the centrifugal type and comprises the shaft Mi mounted in bearings II. Two centrifugal weights I52 are connected by duplicate links I53 to a cross pin I54 extending through the shaft, the weights being shaped as rollers which lie one on each side of the shaft with their axes at right angles to the shaft axis. A collar I55 slidable on the shaft I4I carries two bearing members I55 which extend outwardly between the links I53 and are formed with bearing surfaces I5? preferably perpendicular to the shaft axis upon which the weights I52 can roll. The sliding collar !55 is loaded by a spring I58 which abuts against a second collar I59 fixed to the shaft. A cross pin I65 on the sliding collar I55 extends through a longitudinal slot in the shaft communicating with a bore I6I extending to one end thereof. Slidable longitudinally in the bore IBI is a rod I52, one end of which engages the cross pin I55 and the other end of which protrudes from the shaft and engages an arm I63 on the spindle I 46 through a thrust ball I64. The arrangement is such that at a predetermined speed of the shaft I4! the centrifugal weights I52 move outwards by rolling along the bearing surfaces I5! and thereby displace the sliding collar l55 against its spring loading. This move ment displaces the rod I62 and moves the arm I53 of the V contact member I43 to bring one of the contact studs I45 into engagement with the adjacent contoured contact plate I48 and thereby operate the relay means for effecting a change to a higher gear ratio. When the speed falls to a sufficient extent the sliding collar I55 returns, permitting the V member I43 to move in the opposite direction under the action of a suitable return spring I53a so that contact is made with the other contoured plate and thereby causes a gear changing operation to a lower ratio. It will be understood that the two contact plates I48 correspond to the plates 2 and 3 of Figure 1, and the V contact spring I 44 and studs I45 correspond to the contact arm I of said figure.

A modified form of control circuit, which may be employed in place of the circuit of Figure 1 when desired, is shown in Figure 8. The modified circuit is generally the same as that previously described, but the magnet relays and for the first and second speed magnets 44 and 48 have no back contacts. In place of these, the ratchet switch arm has a contact strip I55 which makes contact with a continuous fixed contact I65 connected to the change-down relay contact I204, and with fixed contacts I81, I68 which occupy the second and third speed positions of the arm respectively and are connected directly to the second and third speed magnets 48 and 52, thereby providing a direct supply for the latter. The supply to the contacts and of these second and third speed magnet relays during a changing-down operation is interrupted by the back contact I 59 on the change-down relay 8. Also during such operation, a supply is provided to the ratchet switch contact strip I through the contacts 9 and I2a on the change-down relay. Thus owing to the fact that the valve actuating magnets 48 and 52 are directly energised without the intervention of their respective relays when changing from a higher to a lower gear, there will be no lag or overlapping of these operations. The relay coils are provided with induction sleeves as in the previous example which afford a lag of about half a second in the operation of the relays, and this is effective when changing from a lower to a higher gear since the magnets are energised through the operation of their respective relays, and hence the desired operational overlapping is obtained.

The modified circuit also has no economising resistance 65 as in the arrangement of Figure 1, and hence additional short-circuiting contacts on the change-up and change-down relays are not required, thereby simplifying the circuit.

t will be seen that when using control means as described above with the selection switch set for automatic operation, an increase in engine speed to a predetermined value causes closing of the governor actuated switch and operation of the automatic selection switch to engage the next higher gear. The introduction of the higher gear reduces the speed of the engine temporarily and causes the governor actuated contacts to open. Converse operations take place when the engine speed falls and the gear ratios are progressively changed-down. If the arrangement is fitted to a vehicle having an automatic clutch or fluid flywheel, the vehicle may be brought to rest by applying the road wheel brakes and the engine can continue to operate at idling speed although the low gear is engaged.

The invention provides a convenient and eifective means enabling manual control of the gear changing operations to be substituted for automatic control when desired, as for example for the purpose of maintaining a low gear in engagement when the vehicle is descending a hill. The invention is not restricted to the example described, since different numbers of gears may be arranged to be controlled by both automatic and manual means. Also the actuation of the gear engaging means may be effected in various ways, for example directly by electro-magnetic means. Further, the invention is not restricted to automatic control dependent upon speed and fuel sup ply or throttle conditions. Thus instead of the governor actuated switch, a pair of push button switches may be provided for example, one controlling a change-up change-down relay or equivalent means, the remainder of the control arrangements being similar to those previously describe What I claim is:

1. Change speed gearing having electrical control means comprising, in combination, two first circuits controlled by contact making members, means adapted to be controlled by a speed sensitive device driven from the input side of the speed gearing for actuating said contact making members to control said circuits alternatively, stepwise actuatable means controlled by one of said first circuits for efiecting engagement of a next higher gear when actuated and controlled by the other of said first circuits for effecting engagement of a next lower gear when actuated, a manually operable selection switch means controlling said first circuits and having rality of positions, further circuits controlled by said selection switch means, and electrical means for controlling engagement of different gear ratios in said further circuits, whereby gear changing is efiected either automatically or by manual selection according to the position of said selection switch means.

2. Change speed gearing according to claim 1, in which the contact making members comprise two elements movable relatively in two nonparallel directions, movement in one direction being controlled by the speed sensitive device, and movement in the other direction being controlled by means responsive to the regulation of the fuel supply to the prime mover.

3. Change speed gearing according to claim 1,

in which the stepwise actuatable means are arranged to actuate a switch mechanism alternatively in opposite directions for controlling difierent circuits for cheating engagement of different gear ratios.

4. Change speed gearing according to claim 1, comprising relays in said first circuits, and a selection switch operable alternatively in opposite directions the stepwise actuatable means to close circuits for actuating the different gear ratio engagement means.

5. Change speed gearing according to 1, comprising relays in said first circuits, a selection switch operable alternatively in opposite clirections by the stepwise actuatable means to close circuits for actuating the different gear ratio engagemnt means, and time relay means such as shunt connected condensers combined with the relays to prevent successive operation thereof within a predetermined period.

relay and the other a 6. Change speed gearing according to claim 1, comprising electro-magnetic devices for controlling engagement of the selected gear.

7. Change speed gearing according to claim 1, comprising electro-magnetic devices for controlling engagement of the selected gears, and electrical relays controlling at least some of said devices.

8. Change speed gearing according to claim 1, comprising electro-magnetic devices for controlling engagement of the selected gears, electrical relays controlling at least some of said devices, and time delay means combined with said relays.

9. Change speed gearing according to claim 1, comprising electro-magnetic devices for controlling engagement of the selected gears, electrical relays controlling at least some of said devices, time delay means combined with said relays, and means for preventing said time delay means from being effective when changing from a higher to a lower gear.

10. Change speed gearing according to claim 1, comprising electro-magnetic devices for controlling engagement of the selected gears, electrical relays controlling at least some of said devices, time delay means combined with said relays, and contacts actuated by one of said relays in a circuit for isolating another relay corresponding to the next higher speed gear when the first said relay is energised, whereby the time delay of said second relay is rendered ineffective and there will be no overlappin of the difierent gear engagement periods when changing from a higher to a lower gear.

11. Change speed gearing according to claim 1, comprising electro-magnetic devices for controlling engagement of the selected gears, electrical relays controlling at least some of said devices, time delay means combined with said relays, an automatic selection switch operated by the stepwise actuatable means, relay means controlling said selection switch, and contacts actuated by said relay means for interrupting the supply of current to the relays controlling the said electromagnetic devices.

12. Change speed gearing according to claim 1, in which the manually operable switch means has contact means automatically engageable each time the switch is operated to change the gear ratio, and a circuit closable by said contact means is associated with an automatic selection switch whereby the positioning of said selection switch in an intermediate position is ensured and thereby inappropriate gear changes are obviated.

13. Change speed gearing according to claim 1, comprising a plurality of gear engaging electrical control devices, a current economising resistance in the circuits of said devices, and means actuated. in response to each gear changing operation for short-circuiting said resistance.

14. Change speed gearing according to claim 1, comprising a plurality of gear engaging electrical control devices, a curr nt economising resistance in the circuit of said devices, means for locking the opera ing handle of the manually operable selection switch means in each selected position, means actuated by unlockin motion of the handle for closing contact means, and circuit means including said contact means for shortcircuiting resistance when the handle is moved from one position to another.

15. Change speed gearing according to claim 1, comprising a plurality of gear engaging electrical control devices, a current economising resistance in the circuit of said devices, an operating handle for the manually operable selection switch means for the manually operable selection switch means arranged for guided movement in a slot of gate form, contact arms associated with the handle and rotatable thereby, means for locking said handle in each selected position, a spring loaded button in said handle for releasing the locking means, means actuated by unlocking motion of the handle for closing contact means, and circuit means including said contact means for shortcircuiting said resistance when the handle is moved from one position to another.

17. Change speed gearing according to claim 1, comprising a plurality of gear engaging electrical control devices, a current economising resistance in the circuit of said devices, an operating handle for the manually operable selection switch means arranged for guided movement in a slot of gate form, depressible contact arms associated with the handle and rotatable thereby, means for looking said handle in each selected position, a spring loaded button in said handle for releasing the locking means and arranged to depress said contact arms when the button is operated, and contacts adapted to be made by depression of said arms for short-circuiting the resistance, the latter being re-introduced when the button is released.

l8. Change speed gearing according to claim 1, in which the contact making members are movable relatively in two directions, movement in one direction being controlled by the speed sensitive device, and movement in another direction being controlled by means responsive to the regulation fuel supply of the prime mover, one of said members comprising a pair of electrically connected contacts mounted in spaced relation for angular movement in unison, and the other of said members comprising a pair of contoured contact plates mounted for angular movement and arranged so that the spaced contacts will make contact with one or other of the plates when relative movement takes place.

19. Change speed gearing according to claim 1, in which the contact making members are movable relatively in two directions, movement in one direction being controlled by the speed sensitive device, and movement in another direction being controlled by means responsive to the regulation of the fuel supply of the prime mover, said contacts comprising a pair of spaced and electrically connected contacts mounted on a V-shaped member for angular movement in unison, said V- shaped member being operable from the speed governor, and a pair of contoured contact plates mounted for angular movement and arranged so that the spaced contacts will make contact with one or other of the plates when relative movement takes place.

20. Change speed gearing according to claim 1, comprising a speed sensitive device having arms carryin centrifugal weights which have rolling engagement with a bearing surface on or associated with a member movable along the axis of weight rotation against resilient loading, the said bearing surface being transverse to said axis so that the displacement of the member is approximately proportional to the change in speed.

21. Change speed gearing according to claim 1, in which the stepwise actuatable means comprise oppositely acting ratchet means combined with a ratchet wheel operating a selection switch.

ALBERT ARTHUR MILLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,100,748 Prince Nov. 30, 1937 2,251,625 Hale Aug. 5, 1941 2,433,099 De Normanville Dec. 23, 1947 2,540,639 Winther et a1 Feb. 6, 1951

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