WO2000018678A1

WO2000018678A1 - Industrial vehicle overhead guard

Info

Publication number: WO2000018678A1
Application number: PCT/US1998/024172
Authority: WO
Inventors: Ralph L. Barnett; Theodore Liber
Original assignee: Triodyne Safety Systems, L.L.C.
Priority date: 1998-09-29
Filing date: 1998-11-12
Publication date: 2000-04-06
Also published as: AU1457399A

Abstract

An overhead guard (11) for an industrial vehicle (10) including a vertical support member (12) having a base end (15) and a top end (16), and a horizontal midplane guard member (13) cantilevered from the top end (16) of the vertical support member (12). A pair of rollover (14) limiting struts disposed perpendicular to the vertical support member (12) and the horizontal midplane guard (13) member is rigidly connected to the vertical support member (12) or the horizontal midplane guard member (13) proximate the top end (16) of the vertical support member (12). A canopy (18) having at least one top plane guard member extends laterally from the horizontal midplane guard member (13). The top plane guard members are resistant to a downward acting force but are retractable, rotatable, or slidable upon tipping of the industrial vehicle (10).

Description

INDUSTRIAL VEHICLE OVERHEAD GUARD

BACKGROUND OF THE INVENTION This invention relates to an overhead guard system for industrial vehicles such as forklift trucks, front end loaders, tractors, bulldozers, compactors, turf trucks, and the like. More particularly, this invention relates to an overhead guard system for industrial vehicles which provides both falling object protection and rollover protection for the vehicle operator and is suitable for use with any industrial vehicle that is typically furnished with an overhead guard as standard or optional equipment. Unlike conventional overhead guards, the overhead guard of this invention will not crush an unrestrained operator during a rollover excursion, even if the operator jumps or is propelled from the seat in the direction of the overturn. This is accomplished by locating the primary load carrying members of the overhead guard in the vertical midplane of the operator's position in the vehicle and by either passively retracting or removing the guard canopy when the vehicle is tipping, or by using a compliant canopy that will not inflict a disabling injury.

DESCRIPTION OF PRIOR ART Current falling object protection structures, (FOPS), or overhead guards, that are incorporated into industrial vehicles such as forklift trucks represent a major hazard during rollover of the vehicle. Conventional overhead guards for industrial vehicles, as shown, for example, by U.S. Patent 3,995,891 and U.S. Patent 5,071,187, all have substantially vertical uprights fastened to the right and left side of the vehicles. In addition, most have a horizontally disposed canopy located above the operator's head. When such an industrial vehicle rolls over, for example, to the left on a flat surface, the conventional overhead guards touch the surface along the left uprights and along the left side of the canopy. As operators jump, climb, or are thrown from the seat during a rollover excursion, their bodies fall into the trajectory of the canopy and/or the uprights, sandwiching them between the ground or operating surface and the canopy and/or uprights, resulting in a crushing injury.

To protect operators against this contingency, the seatbelt has become the intervention system of choice. The simplest geometric considerations demonstrate that the seatbelt will fully protect an operator's head and torso from the overhead guard. Testing of forklift trucks reveals that occasionally a limb will be pinched by an upright. On unimproved surfaces, safety professionals generally agree that the seatbelt provides an effective countermeasure. The seemingly intractable problem is the low seatbelt usage on industrial vehicles.

Standards for overhead guards for high lift rider powered industrial trucks are set forth by the American National Standards Institute in the publication entitled "Safety Standard for Low Lift and High Lift Trucks,"ASME/ANSI B56.1- 1993. Sections 7.27.1 and 7.27.2 of these standards require that an overhead guard and its mounting be capable of withstanding the impact of a 100 pound hardwood covered cube, or its equivalent, dropped in free-fall vertically from a distance of five feet ten times without fracture and without permanent deformation exceeding 0.75 inches based on the original head clearance provided by the guard. In addition, the standards require that the overhead guard and its mounting be capable of withstanding an impact test in which a test load comprising a bundle of 2 X 4 normal construction grade lumber 12 feet long and not exceeding 40 inches in width and with an aggregate specified minimum weight is dropped onto the overhead guard in free-fall from an approximate horizontal position and from a height sufficient to develop a required impact in foot-pounds. For sit-down rider trucks, the permanent deformation of the overhead guard and its mounting after impact is measured between a horizontal plane tangent to the underside of the guard at the operator's position and a horizontal plane tangent to the upper surface of the steering wheel and must not be less than 10 inches between the planes. For stand-up rider trucks, the permanent deformation of the overhead guard and its mounting after impact must leave a distance of not less than 64 inches between the surface on which the operator stands during truck operation and the horizontal plane tangent to the underside of the overhead guard.

Standards for rollover protective structures (ROPS) are set forth in the Society for Automotive Engineering Standard SAE J1040 May 94. In general, such structures must be force resistant in the lateral, vertical, and longitudinal directions, and energy absorptive in the lateral direction. The standards set forth limitations on deflections under lateral, vertical, and longitudinal loading. The standards are intended to ensure that the rollover protective structure will deflect when it impacts a surface which will not significantly deform while retaining significant capability to withstand subsequent impacts in an overturn.

SUMMARY OF THE INVENTION

It is one object of this invention to provide an overhead guard for industrial vehicles which is fully compliant with the standards for falling object protective structures and rollover protective structures for industrial vehicles. It is one object of this invention to provide an overhead guard for industrial vehicles which avoids crushing injuries to operators caused by conventional overhead guards during the course of a rollover of the industrial vehicle.

It is another object of this invention to provide an overhead guard for industrial vehicles which eliminates the need for an operator to wear a seatbelt.

These and other objects of this invention generally are achieved by an overhead guard for an industrial vehicle comprising an arrangement of elements which provides compliance with a FOPS requirement for said industrial vehicle and which produces a headform acceleration having a Head Injury Criterion value in the range of about 0 to about 1000 as a result of a slowly induced vehicle roll without vehicle translation (quasi-static initial conditions) upon contact with a rigidly mounted standard adult anthropomorphic impact headform.

More particularly, these and other objects of this invention are achieved in accordance with one embodiment of this invention by an overhead guard for an industrial vehicle comprising a substantially vertical support member having a base end and a top end, the base end being suitable for attachment to the industrial vehicle. A substantially horizontal midplane guard member is cantilevered from the top end of the vertical support member and constitutes the foundational member for the falling object protection structure. A pair of rollover limiting struts disposed perpendicular to the vertical support member and the horizontal midplane guard member and extending to a width of the industrial vehicle are rigidly connected on opposite sides of a vertical midplane formed by the vertical support member and the horizontal midplane guard member to the vertical support member or the horizontal midplane guard member proximate the top end of the vertical support member. These rollover limiting struts are the basic elements of the rollover protection structure (ROPS) comprising the overhead guard of this invention. The overhead guard further comprises a canopy comprising at least one top plane guard member extending laterally from the horizontal midplane guard member on both sides of the vertical midplane formed by the vertical support member and the horizontal midplane guard member, in which at least one top plane guard member is resistant to a downward acting force, yet, in accordance with at least one embodiment, provides for retraction or removal of the canopy in the event of an industrial vehicle rollover. As used throughout the specification and claims, the term "midplane" is intended to refer to a longitudinal vertical plane that includes the longitudinal centerline of the operator's seat and, thus, the operator's head when normally seated. Thus, for industrial vehicles with operator seats disposed along the centerline of the vehicles, the midplane will include the centerline of both the operator's seat and the industrial vehicle. However, for industrial vehicles having operator seats which are offset from the vehicle centerline, the midplane will include the centerline of the operator seat but not include the centerline of the vehicle.

As used throughout the specification and claims, the term "Head Injury Criterion" or "HIC" is defined in accordance with the following equation:

where is the acceleration-time history of a headform in its fore and aft direction during the impact phase of a rollover event, a^, is the associated acceleration-time history in the orthogonal left and right headform direction, a^ is the corresponding acceleration-time history in the orthogonal up and down headform direction, t, is the beginning of an arbitrary time interval, and t₂ is the end of the time interval.

In accordance with one embodiment, the canopy comprises at least one top plane guard member in the form of a rigid grillage which, during rollover, is moved or retracted or rotated or shifted into a position where it cannot contact an operator who dismounts the vehicle in the rollover direction. In accordance with another embodiment, the canopy comprises a plurality of top plane guard members extending laterally from the horizontal midplane guard member on both sides of the midplane. In accordance with yet another embodiment of this invention, at least a portion of said canopy is frangible. BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of this invention will be better understood from the detailed description that follows and taken in conjunction with the drawings wherein:

Fig. 1 is a diagram of a side view of a forklift truck showing the basic structural members of the falling object protection structure of the overhead guard of this invention; Fig. 2 is a diagram of a top view of a forklift truck rolled onto its side showing the basic structural members of both the falling object protection structure and the rollover protection structure of the overhead guard of this invention;

Fig. 3 is a diagram showing an end view of an industrial vehicle rolled onto its side with the overhead guard in accordance with one embodiment of this invention in contact with a rigidly mounted headform;

Fig. 4 is a perspective view of a forklift truck with an overhead guard in accordance with one embodiment of this invention;

Fig. 5 is a rear view of the forklift truck with overhead guard shown in Fig. 4;

Fig. 6 is a top view of a portion of the falling object protection structure of an overhead guard in accordance with one embodiment of this invention;

Fig. 7 is a top view of a portion of the falling object protection structure of an overhead guard in accordance with another embodiment of this invention;

Fig. 8 is a top view of a portion of the falling object protection structure of an overhead guard in accordance with one embodiment of this invention;

Fig. 9 is a perspective view of a portion of the falling object protection structure of an overhead guard in accordance with one embodiment of this invention;

Fig. 10 is a top view of a portion of the falling object protection structure of an overhead guard in accordance with the embodiment shown in Fig. 9;

Fig. 11 is a perspective view of the falling object protection structure of an overhead guard in accordance with one embodiment of this invention;

Fig. 12 is a perspective view of a variant of the falling object protection structure of an overhead guard in accordance with the embodiment of this invention shown in Fig. 11;

Fig. 13 is a perspective view of a portion of the falling object protection structure of an overhead guard in accordance with one embodiment of this invention;

Figs. 14a, 14b, and 14c depict operation of the portion of the falling object protection structure of the overhead guard shown in Fig. 13 during tipping of an industrial vehicle;

Fig. 15 is a perspective view of a portion of the falling object protection structure of an overhead guard in accordance with one embodiment of this invention; Fig. 16 is a frontal view of a portion of the falling object protection structure of an overhead guard in accordance with one embodiment of this invention;

Fig. 17 is a top view of an overhead guard employing a grillage-style canopy in accordance with one embodiment of this invention;

Fig. 18 is a view of the overhead guard shown in Fig. 17 in the direction of the arrows of the line A-A;

Fig. 19 is a perspective view of an overhead guard employing a grillage-style canopy in accordance with one embodiment of this invention;

Figs. 20a and 20b are side views of the overhead guard shown in Fig. 19 showing operation of the grillage-style canopy so as to avoid striking of an operator during a vehicle rollover;

Fig. 21 is a front view of the overhead guard shown in Fig. 20a in the direction of the arrows of the line A-A;

Figs. 22a and 22b show a top view of an overhead guard having a retractable grillage-style canopy in accordance with one embodiment of this invention;

Fig. 23 is a perspective view of the skeletal structure for an overhead guard in accordance with one embodiment of this invention;

Fig. 24 is a front view of the overhead guard shown in Fig. 23 viewed in the direction of the arrows of the line A-A with a slidable canopy disposed thereon;

Figs. 25a and 25b show a top view of an overhead guard showing the slide kinematics of the grillage-style canopy in accordance with one embodiment of this invention; Fig. 26 is a perspective view of the skeletal portion of an overhead guard in accordance with one embodiment of this invention;

Fig. 27 is a side view of the overhead guard shown in Fig. 26 with a slidable canopy disposed thereon; and

Fig. 28 is a top view of the overhead guard shown in Figs. 26 and 27 showing the slide kinematics of the grillage-style canopy in accordance with one embodiment of this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS As previously indicated, during rollover of an industrial vehicle equipped with a conventional overhead guard, the overhead guard constitutes a crushing hazard between the vehicle operating surface and the side edges of the canopy and the side mounted uprights. The overhead guard of this invention eliminates the side mounted uprights of conventional overhead guards and, thus, their associated dangers by location of a single upright in the longitudinal midplane of the industrial vehicle as shown in Figs. 1 and 2. Industrial vehicle 10, depicted as a forklift truck, comprises an overhead guard 11 in accordance with this invention having both a falling object protection structure and a rollover protection structure. It will be apparent to those skilled in the art that, although shown herein as being applied to a forklift truck, the overhead guard of this invention may be applied to any industrial vehicle requiring falling object protection and rollover protection including front end loaders, tractors, bulldozers, compactors, and turf trucks.

The overhead guard of this invention may be produced from any suitable materials formed into weight reducing structural shapes.

As shown in Figs. 1 and 2, overhead guard 11 comprises substantially vertical support member 12 having base end 15 and top end 16, base end 15 being suitable for attachment to the industrial vehicle 10. For example, base end 15, as shown in Figs. 1 and 2, may be provided with base plate 17 which is bolted to the industrial vehicle body. To provide falling object protection, overhead guard 11 further comprises substantially horizontal midplane guard member 13 cantilevered from top end 16 of vertical support member 12. For all applications of the overhead guard of this invention, horizontal midplane guard member 13 is disposed in a vertical longitudinal plane that contains the centerline of the operator's seat of the industrial vehicle and, thus, the centerline of an operator's head when the operator is normally seated. Horizontal midplane guard member 13 thus forms the main load resisting member of the falling object protection structure of the overhead guard of this invention.

To provide rollover protection, a pair of rollover limiting struts 14 disposed perpendicular to vertical support member 12 and horizontal midplane guard member 13 and extending to the width of the industrial vehicle are rigidly connected on opposite sides of the midplane formed by vertical support member 12 and horizontal midplane guard member 13 to either vertical support member 12 or horizontal midplane guard member 13 proximate to the top end 16 of vertical support member 12. Connected to the free end of each rollover limiting strut is a force distribution plate 19. In this manner, as shown in Fig. 2, rollover of industrial vehicle 10 is restricted to about 90° and maintains a safety gap in the rolled over condition of the vehicle indicated by arrow 24 between horizontal midplane guard member 13 and the operating surface 26 which is approximately half the width of industrial vehicle 10. As a result, the potential for crushing of the vehicle operator between the overhead guard 11 and the operating surface 26 is eliminated. It will be apparent to those skilled in the art that, for certain industrial vehicles such as forklift trucks, rollover protection is afforded, at least to some extent, by the mast thereof. In such cases, inclusion of the rollover protection structure in the form of rollover limiting struts 14 in the overhead guard of this invention is optional.

Alternatively to, or in addition to, the rollover protection structure, the overhead guard of this invention is designed in such a fashion that, in additon to satisfying its FOPS requirements, in a worst case impact scenario involving a slowly induced roll without vehicle translation, the impact of the canopy elements comprising the overhead guard with a rigidly mounted standard adult anthropomorphic impact headform, as shown in Fig. 3, having two inches of clearance above a flat horizontal surface, will not give rise to resultant headform accelerations greater than a Head Injury Criterion (HIC value) of about 1000.

To prevent falling objects from striking the vehicle operator, the overhead guard of this invention further comprises a canopy comprising at least one top plane guard member movably connected to and extending laterally from horizontal midplane guard member 13 on both sides of the midplane formed by horizontal midplane guard member 13 and vertical support member 12, which top plane guard members are resistant to a downward acting force. As shown in the embodiments of Figs. 4 and 5, the canopy comprises a plurality of such top plane guard members 18. In accordance with another embodiment shown in Figs. 17 and 19, the top plane guard member is in the form of a rigid grillage connected to the horizontal midplane guard member 13 and/or the rollover limiting struts 14. The canopies thus formed are retractable or removable upon tipping of the industrial vehicle to prevent them from entering the safety gap 24 shown in Fig. 2 upon a rollover incident.

In accordance with one preferred embodiment of this invention, shown in Figs. 4 and 5, horizontal midplane guard member 13 is a cantilevered longitudinal circular tube to which a plurality of top plane guard members 18 are vertically rotatably connected, thereby forming a grid or mesh structure to intercept falling objects that could enter the operator's space. Top plane guard members 18 are formed using lightweight materials and weight reducing structural forms and comprise a ring structure at one end fitted around circular tube/horizontal midplane guard member 13. If subjected to upward force components, top plane guard members 18 will rotate freely about circular tube/horizontal midplane guard member 13, thereby limiting the force transmitted to a victim in a rollover crush scenario. The direction of free rotation of top plane guard members 18 is indicated by arrows 27 shown in Fig. 5. It should be noted that only a few of top plane guard members 18 will typically contact a victim in a given rollover incident; thus, impact is limited to the weight of only a few lightweight members.

Resistance of top plane guard members 18 to a downward acting force in accordance with the embodiment shown in Figs. 4 and 5 is provided by stops 19, 28 as shown in Fig. 5. Thus, when falling objects contact top plane guard members 18, downward rotation of top plane guard members 18 is prevented by stops 19, 28. As can clearly be seen, the overhead guard of this invention provides both falling object protection and rollover protection and maintains a "non-crushing" distance from the vehicle operating surface even during rollover. This is the direct opposite of conventional rollover protection systems. There are also no vertical members that can contact or crush a victim as in the case of conventional systems. Finally, blind spots associated with the vertical members in conventional overhead guard systems are entirely eliminated by this invention.

In accordance with another embodiment of this invention, top plane guard members 18 are hingedly connected to horizontal midplane guard member 13 whereby top plane guard members 18 will rotate, either horizontally or vertically, during a rollover event. In accordance with one embodiment shown in Fig. 6, top plane guard members 18 are connected to horizontal midplane guard member 13 by horizontal hinge 20 and hinge pin 25. In accordance with the embodiments shown in Fig. 7, top plane guard members 18 are connected to horizontal midplane guard member 13 by near side vertical hinges 22. In accordance with yet another embodiment as shown in Fig. 8, top plane guard members 18 are connected to horizontal midplane guard member 13 by far side vertical hinges 23. In accordance with this latter embodiment, horizontal midplane guard member 13 acts as a stop which prevents top plane guard members 18 from rotating downward when acted upon by a downwardly acting force, such as a falling object.

In accordance with one embodiment of the overhead guard of this invention, horizontal midplane guard member 13 forms a plurality of slots 21 as shown in Fig. 9. Top plane guard members 18 are slidably disposed within slots 21, thereby providing a very effective method of resisting downward acting forces. In accordance with one embodiment, as shown in Figs. 9 and 10, slots 21 are formed by horizontal midplane guard member 13 in a manner whereby the top plane guard members 18 inserted in slot 21 are disposed at a horizontal angle as shown in Fig. 9.

As shown in Figs. 9 and 10, none of these slidably connected top plane guard members 18 will rotate downward and, thus, will all resist falling objects. Rather, top plane guard members 18 will come in contact with the operating surface during a rollover. However, due to the slidability of these members within the horizontal midplane guard member 13, these members can be equipped to automatically retract during the tipping phase of a rollover incident so that no impact or crushing hazard can occur by them. Similarly, in accordance with the embodiments shown in Figs. 11 and 12, top plane guard members 18 are horizontally slidably connected to horizontal midplane guard member 13 in a manner which enables top plane guard members 18 to slide freely in the transverse direction. As in the embodiment shown in Figs. 9 and 10, top plane guard members 18 are resistant to a downward acting force, which resistance is not compromised by their sliding capability. If sliding top plane guard members 18 are struck in a rollover event, the slidable members will simply push into horizontal midplane guard member 13 and impose a limited impact on an operator who might be caught in the trajectory of the falling object protection structure. Only those top plane guard members striking the operator will slide, thereby limiting the total weight of the falling object protection structure striking the victim. To further reduce the mass of the striking top plane guard members, sliding top plane guard members 18, as shown in Fig. 11, are staggered.

Fig. 13 shows one embodiment of the overhead guard of this invention having means for rotating top plane guard members 18 into a vertical upward direction during the tipping phase of an industrial vehicle rollover so that no impact or crushing hazard occurs to the operator. Using a continuous hinge pin 25 as shown in Fig. 13, a pendulum or vertical weight 31 is rigidly fastened to continuous hinge pin 25. Tipping of horizontal midplane guard member 13 in a counterclockwise direction produces the same action as rotating hinge pin 25 clockwise. Top plane guard members 18 remain in a horizontal position during tipping of the industrial vehicle because the weight of pendulum 31 maintains a vertical attitude as shown in Figs. 14a, 14b, and 14c. Fig. 14a shows the system at 0° tipping; Fig. 14b shows the system at a 45° tip angle; and Fig. 14c shows the system at a 90° tip angle.

Accordingly, as shown in Fig. 13, in accordance with one embodiment of this invention, the overhead guard comprises pendulum means for rotating at least one of the top plane guard members 18 in an upward direction upon tipping of the industrial vehicle. The pendulum means comprises a hinge 23 having a hinge pin 25 connecting top plane guard member 18 to horizontal midplane guard member 13, pendulum 31 rigidly connected to hinge pin 25, lifting bar 32 disposed parallel to top plane guard member 18 and having one end connected to hinge pin 25, and stop bar 33 extending peφendicular to top plane guard member 18 and contacting a top side of lifting bar 32, one end of stop bar 33 being connected to top plane guard member 18. Furthermore, top plane guard member 18 has an overhang 74 which restricts the rotation of top plane guard member 18 to somewhat less than but close to 90° in the clockwise direction.

It will be apparent to those skilled in the art that the embodiment of the overhead guard of this invention shown in Fig. 13 includes the following features: (1) any top plane guard member 18 can be independently rotated within the limits imposed by the horizontal midplane guard member 13 and the overhang 74; (2) when the vehicle is in its upright position, the top plane guard members 18 individually and collectively cannot be rotated, i.e., lifted, to a complete vertical attitude because of the restriction imposed by the overhangs 74. Consequently, when gravity alone is acting on such a top plane guard member 18 in the vehicle upright position, the top plane guard member 18 cannot maintain a vertical attitude and will, by gravitational action, tend to return to contact with the horizontal midplane guard member 13; (3) the pendulum 31 can be sized such that during tipping of the vehicle in the direction of the top plane guard members 18 due to a rollover incident, all top plane guard members 18 will be rotated relative to the horizontal midplane guard member 13 by the passive medium of gravity acting on the pendulum 31 ; (4) furthermore, the pendulum can be sized such that during tipping of the vehicle in the direction of the top plane guard members 18 due to a rollover incident, gravity will tend to keep the pendulum 31 vertical, with the consequence that all top plane guard members 18 will be rotated relative to the horizontal midplane guard member 13 by the gravitational action of the pendulum in such a way as to maintain their initial horizontal attitude, hence will not encroach the operator safety gap 24 shown in Fig. 2; (5) because the top plane guard members 18 can be independently rotated only within the limits imposed by the horizontal midplane guard member 13 and the overhangs 74, and because the vehicle rollover is limited to 90° by the rollover limiting struts 14 shown in Fig. 2, the top plane guard members 18 will not invade the operator safety gap 24 of Fig. 2 during either a counterclockwise or clockwise rollover incident; (6) because of the overhang 74, the top plane guard members 18 will not invade the previously mentioned operator safety gap 24 during an opposite side (clockwise for Fig. 13) rollover incident, hence any whipping action (double pendulum effect) by the top plane guard members 18 due to such a rollover is contained to the space above the operator safety gap 24; (7) the vehicle canopy top plane guard members 18 do not compromise the operator safety gap 24 of Fig. 2, making crushing and impact within the safety gap due to a rollover incident an impossibility; and (8) any impact which may occur outside of the safety gap may be mitigated through the use of lightweight padded top plane guard members 18.

In accordance with another embodiment of this invention, as shown in Fig. 15, top plane guard members 18, to limit the forces ti nsferred by them in a downward direction, are countersprung by a helical spring counterweight system acting in an upward direction comprising hinge 23 and hinge pin 25 connecting top plane guard member 18 to horizontal midplane guard member 13 and helical spring 34 disposed around hinge pin 25 having tangs 35 and 36 in contact with top plane guard member 18 and horizontal midplane guard member 13 whereby top plane guard member 18 and helical spring 34 counterweigh each other with respect to horizontal midplane guard member 13.

It will also be apparent to those skilled in the art that other mechanisms may also be employed to retract any of the top plane guard members. As indicated hereinabove, top plane guard members 18 may be raised vertically or they may be rotated against horizontal midplane guard member 13 (Fig. 6). The mechanisms may be driven by compressed air, explosives or springs, all of which may be activated during a vehicle rollover incident by tilt indicators and detectors set for critical tilt angles.

Yet another embodiment of a top plane guard member for use in the overhead guard of this invention is shown in Fig. 16. Top plane guard member 18 comprises a flex band 40, such as a webbing, plastic or steel mesh, and a plurality of light weight tubing segments 41 attached to an underside of flex band 40 by attachment means 42. Disposed between attachment means 42 are areas 43 of flex band 40 which are free of any attachment means whereby flex band 40 will bend upwardly at said areas when acted upon by an upwardly acting force. In accordance with one embodiment of this invention, the tubing segments 41 are height graded with the shorter height segments disposed toward the free end of top plane guard member 18. In accordance with another embodiment of this invention, the flex band 40 is replaced with any of a variety of hinge elements connecting the tubing elements 41.

In accordance with one preferred embodiment of the overhead guard of this invention, horizontal midplane guard member 13 and rollover limiting struts 14 provide a foundation that supports a canopy in the form of a rigid grillage 50, as shown in Figs. 17, 18, 19, 25a, 25b, and 28, which covers the operator's station of the industrial vehicle and resists falling objects. Rigid grillage 50 is connected to horizontal midplane guard member 13 and/or rotation limiting struts 14 such that, during vehicle rollover, grillage 50 is moved or retracted, or rotated or shifted, into a position where it cannot contact an operator dismounting the vehicle in the rollover direction.

For all of these canopy embodiments, the retraction, rotation or shifting into position is accomplished by gravity forces or stored energy which move the grillage 50 out of the way of the operator safety gap 24 shown in Fig. 2 whenever the vehicle tilt angles exceed predetermined settings, thereby precluding a vehicle operator from being struck by grillage 50 during the course of a rollover incident. Various tilt meters which are known to those skilled in the art for use as safety devices in aerial lifts to prevent overturns may be used to indicate critical angles for the overhead guard of this invention.

As shown in Fig. 18, rigid grillage 50 is fabricated in two sections, each of which is vertically rotatably connected by hinges 51 to horizontal midplane guard member 13. Alternatively, in accordance with one embodiment of this invention as shown in Fig. 19, rigid grillage 50 is fabricated as a single unit which is vertically rotatably connected by hinges 52 to rollover limiting struts 14. As shown in Figs. 20a and 20b, rigid grillage 50 will rotate vertically around hinges 52 during a rollover incident. To provide torsion resistance when struck by a falling object, braces 53 are secured to the underside of rigid grillage 50 on both sides of horizontal midplane guard member 13 as shown in Fig. 21.

Figs. 22a and 22b show a retractable grillage 55 fixedly connected to rollover limiting struts 14. In its normal protective position, as shown in Fig. 22a, retractable grillage 55 extends over horizontal midplane guard member 13, thereby providing the vehicle operator with protection against falling objects. During a rollover incident, retractable grillage 55 retracts in the direction of rotation limiting struts 14, as shown in Fig. 22b, so as to avoid striking of an operator dismounting from the vehicle during the rollover incident. In accordance with one embodiment of this invention, rigid grillage 50 is slidably connected to horizontal midplane guard member 13 and rollover limiting struts 14 by a captured type track system comprising tracks 60 and runner 61 whereby rigid grillage 50 is slidable, either longitudinally or transversely with respect to horizontal midplane guard member 13 during a vehicle rollover incident. As shown in Fig. 23, tracks 60 are fixedly secured to the top surfaces of horizontal midplane guard member 13 and rotation limiting struts 14 in a direction parallel to horizontal midplane guard member 13. Runners 61 corresponding to tracks 60, as shown in Fig. 24, are secured to the underside of rigid grillage 50 and slidably engage track 60. As shown in Fig. 25a, in the normal protective position, rigid grillage 50 is disposed over horizontal midplane guard member 13, thereby providing falling object protection for the vehicle operator. During the course of a rollover incident, rigid grillage 50 is longitudinally slidable as shown in Fig. 25b in the direction of rotation limiting struts 14, thereby precluding a dismounting operator from being struck by rigid grillage 50 during the course of a rollover incident.

Figs. 26, 27 and 28 show an alternative embodiment of an overhead guard to the embodiment shown in Figs. 23, 24, 25a and 25b whereby rigid grillage 50 is transversely slidable with respect to horizontal midplane guard member 13. In accordance with this embodiment, tracks 60 are secured to the top side of horizontal midplane guard member 13 and rollover limiting struts 14 in a direction peφendicular to horizontal midplane guard member 13 to which rigid grillage 50 is slidably connected by track 61. In accordance with this embodiment, rigid grillage 50 slides transversely with respect to horizontal midplane guard member 13 during a rollover incident as shown in Fig. 28. It will be apparent to those skilled in the art that, although shown with the tracks connected to the structural elements comprising the overhead guard foundation and the runners connected to the rigid grillage 50, an embodiment in which the runners are connected to the structural elements comprising foundation of the overhead guard and the tracks are connected to the underside of the rigid grillage is also feasible.

While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for puφose of illustration, it will be apparent to those skilled in the art that the invention is capable of additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.

Claims

WE CLAIM:

1. An overhead guard for an industrial vehicle comprising: a substantially vertical support member having a base end and a top end, said base end suitable for attachment to said industrial vehicle; a substantially horizontal midplane guard member cantilevered from said top end of said vertical support member; and a canopy comprising at least one top plane guard member extending laterally from said horizontal midplane guard member on both sides of a midplane formed by said vertical support member and said horizontal midplane guard member and resistant to a downward acting force, at least a portion of said canopy being at least one of retractable, rotatable, and slidable upon tipping of said industrial vehicle.

2. An overhead guard in accordance with Claim 1 further comprising a pair of rollover limiting struts disposed peφendicul.ar to said vertical support member and said horizontal midplane guard member extending to a width of said industrial vehicle rigidly connected on opposite sides of said midplane to one of said vertical support member and said horizontal midplane guard member proximate said top end of said vertical support member.

3. An overhead guard in accordance with Claim 1, wherein said canopy comprises a plurality of said top plane guard members which are rotatably connected to said horizontal midplane guard member.

4. An overhead guard in accordance with Claim 1, wherein said at least one top plane guard member is one of transversely and longitudinally slidably connected to said horizontal midplane guard member.

5. An overhead guard in accordance with Claim 2, wherein said at least one top plane guard member is vertically rotatingly connected to said rollover limiting struts.

6. An overhead guard in accordance with Claim 2, wherein a force distribution plate is connected to a free end of each said rollover limiting strut.

7. An overhead guard in accordance with Claim 1, wherein said at least one top plane guard member is vertically rotatable.

8. An overhead guard in accordance with Claim 7 further comprising pendulum means for rotating at least one of said top plane guard members in an upward direction upon tipping of said industrial vehicle.

9. An overhead guard in accordance with Claim 4, wherein said at least one top plane guard member is transversely slidably connected to said horizontal midplane guard member, said horizontal midplane guard member forming at least one slot and said at least one top plane guard member being inserted into said at least one slot.

10. An overhead guard in accordance with Claim 2, wherein said at least one top plane guard member is one of transversely and longitudinally slidably connected to at least one of said horizontal midplane guard members and said rollover limiting struts.

11. An overhead guard in accordance with Claim 10, wherein said at least one top plane guard member is connected to at least one of said horizontal midplane guard members and said rollover limiting struts by a track system.

12. An overhead guard in accordance with Claim 3, wherein said top plane guard members are hingedly connected to said horizontal midplane guard member by one of a far side vertical hinge, a near side vertical hinge, a top side hinge and a horizontal hinge.

13. An overhead guard in accordance with Claim 8, wherein said pendulum means comprises at least one far side vertical hinge having a hinge pin, said at least one far side vertical hinge connecting each said top plane guard member to said horizontal midplane guard member, and said hinge pin being a continuous hinge pin extending through each of said hinges, a pendulum connected to said hinge pin, at least one lifting bar disposed parallel to said top plane guard members and having one end connected to said hinge pin, and at least one stop bar extending peφendicular to said top plane guard members and contacting a top side of said lifting bar, one end of said at least one stop bar being connected to said top plane guard member.

14. An overhead guard in accordance with Claim 1 further comprising a stop connected to said horizontal midplane guard member, said stop preventing a downward movement of said top plane guard members when acted upon by a downward acting force.

15. An overhead guard in accordance with Claim 1 , wherein said horizontal midplane guard member is a circular tube and said top plane guard members comprise a ringed end portion, said ringed end portion disposed around said circular tube.

16. An overhead guard in accordance with Claim 5 further comprising at least one torsion resistance brace connected to an underside of said at least one top plane guard member adjacent to each side of said horizontal midplane guard member.

17. An overhead guard in accordance with Claim 1, wherein each of said top plane guard members comprises a plurality of tubing segments attached to an underside of a flex band.

18. An overhead guard in accordance with Claim 17, wherein each of said top plane guard members comprises a plurality of segments attached to each other by at least one hinge element.

19. In an industrial vehicle having a vehicle body, operator vehicle controls, an operator position, and an overhead guard disposed over said operator position providing falling object protection and rollover protection to an operator in said operator position, the improvement comprising:

.an overhead guard comprising a substantially vertical support member having a base end and a top end, said base end attached to said vehicle body, a substantially horizontal midplane guard member cantilevered from said top end of said vertical support member and extending over a longitudinal midplane of said operator position, and a canopy disposed over said operator position comprising at least one top plane guard member extending laterally from said horizontal midplane guard member on both sides of a midplane formed by said vertical support member and said horizontal midplane guard member to one of said vertical support member and said horizontal midplane guard member proximate said top end of said vertical support member, and resistant to a downward acting force, at least a portion of said canopy being at least one of retractable, rotatable, and slidable upon tipping of said industrial vehicle.

20. An industrial vehicle in accordance with Claim 19 further comprising a pair of rollover limiting struts disposed peφendicular to said vertical support member and said horizontal midplane guard member extending to a width of said industrial vehicle fixedly connected on opposite sides of said midplane.

21. An industrial vehicle in accordance with Claim 19, wherein said at least one top plane guard member is rotatably connected to said horizontal midplane guard member.

22. An industrial vehicle in accordance with Claim 20, wherein said at least one top plane guard member is vertically rotatably connected to one of said horizontal midplane guard member and said rollover limiting struts.

23. An industrial vehicle in accordance with Claim 20, wherein said top plane guard members are one of transversely and longitudinally slidably connected to at least one of said horizontal midplane guard member and said rollover limiting struts.

24. An industrial vehicle in accordance with Claim 20, wherein a force distribution plate is connected to a free end of each said rollover limiting strut.

25. An industrial vehicle in accordance with Claim 21 further comprising pendulum means for rotating at least one of said top plane guard members in an upward direction upon tipping of said industrial vehicle.

26. An industrial vehicle in accordance with Claim 21, wherein said top plane guard members are hingedly connected to said horizontal midplane guard member by one of a far side vertical hinge, a near side vertical hinge, a top side hinge and a horizontal hinge.

27. An industrial vehicle in accordance with Claim 25, wherein said pendulum means comprises at least one far side vertical hinge having a hinge pin, said at least one far side vertical hinge connecting each said top plane guard member to said horizontal midplane guard member and said hinge pin being a continuous hinge pin extending through each of said hinges, a pendulum connected to said hinge pin, at least one lifting bar disposed parallel to said top plane guard members and having one end connected to said hinge pin, and at least one stop bar extending peφendicular to said top plane guard members and contacting a top side of said at least one lifting bar, one end of said at least one stop bar being connected to said top plane guard member.

28. An industrial vehicle in accordance with Claim 19 further comprising a stop connected to said horizontal midplane guard member, said stop preventing a downward movement of said top plane guard members when acted upon by a downward acting force.

29. An industrial vehicle in accordance with Claim 19, wherein said horizontal midplane guard member is a circular tube and said top plane guard members comprise a ringed end portion, said ringed end portion disposed around said circular tube.

30. An overhead guard for an industrial vehicle comprising: an arrangement of elements which provides compliance with a FOPS requirement for said industrial vehicle and which produces headform accelerations which give rise to a Head Injury Criterion value in a range of about 0 to about 1000 as a result of a slowly induced vehicle roll without vehicle translation upon contact with a rigidly mounted standard adult anthropomoφhic impact headform.

31. An overhead guard in accordance with Claim 30, wherein said arrangement of elements comprises a plurality of grillage elements which act independently in one of an upward loading and a downward loading direction.

32. An overhead guard in accordance with Claim 30, wherein said arrangement of elements comprises a plurality of grillage elements which behave as statically determinate beams when loaded in a downward direction and as mechanisms when loaded in an upward direction.

33. An overhead guard in accordance with Claim 30, wherein said arrangement of elements comprises a plurality of independently acting bending elements which are at least one of counterweighted and countersprung so as to limit forces transferred in a downward direction.

34. An overhead guard in accordance with Claim 31, wherein at least a portion of said arrangement of elements is padded.

35. An overhead guard in accordance with Claim 31, wherein said arrangement of elements comprises a plurality of independently acting bending elements of which at least one is segmented and articulated, providing a statically determinate behavior in a downward direction and a mechanism behavior in an upward direction.

36. An overhead guard in accordance with Claim 31, wherein said arrangement of elements comprises a plurality of independently acting bending elements at least one of geometrically oriented, shaped and curved whereby said bending elements move upward relative to said vehicle upon striking any rigid horizontal surface during a rollover of said vehicle.

37. An overhead guard in accordance with Claim 30, wherein at least a portion of said arrangement of elements is frangible.