Dock leveler with automatic vehicle barrier

Abstract: A dock leveler assembly is provided having an automatic barrier actuated in response to movement of the lip for preventing accidental runoff of material handling vehicles from the loading dock. The assembly includes a ramp (12) for pivotal movement between a stored first position wherein an exposed surface thereof is coplanar with the loading dock platform surface, an upwardly inclined second position, and a declining third position. The lip (18) is operatively connected to a front edge portion (12a) of the ramp (12) for movement from a depending position to an outwardly extended cantilevered position. The assembly also includes a barrier unit (30) movable between operative and inoperative modes. When in the operative mode, a segment of the barrier unit (30) automatically projects above the ramp exposed surface and forms a vehicle safety barrier of optimum height.

Description: This invention relates to a loading dock leveler according to the preamble of claim 1 and more particularly to a dock leveler assembly which when in one mode automatically provides a barrier to prevent material handling equipment from accidentally running off the exposed front end of the loading dock. Loading dock levelers, sometimes called dockboards, are used to facilitate the loading and unloading of variously sized vehicles which are parked adjacent to a loading dock that has a working surface above the roadway adapted to adjoin the bed of a parked vehicle. Examples of loading dock leveler assemblies are disclosed in US-As-3,583,014, 3,699,601, 3,728,753, 4,110,860, 4,257,137, 4,531,248, 4,570,277 and 4,744,121. Such dock levelers compensate for height variations between the bed of the parked vehicle and the working sometimes referred hereafter as platform surface, surface of the dock since they are typically disposed in a pit or recess at the front of the loading dock and include a ramp pivotal between a raised position above the working surface of the dock and a below dock level position. An extension plate or lip is hinged to the front edge of the ramp and is movable to an extended position to span the gap between the bed of the parked vehicle and the front edge of the ramp. When such dock levelers are not in use, they are stored in a cross-traffic position having the an exposed upper surface of ramp flush with the working surface of the dock and the lip disposed in a depending position. In the practical implementation of such dock levelers certain safety problems may arise. Loading dock personnel may accidentally drive or push fork lift trucks or related material handling equipment off the exposed front end of the dock leveler when there is no vehicle parked adjacent the loading dock and the dock leveler is stored in the cross-traffic position. Dock levelers have heretofore been provided to minimize the risk of such accidental run off. Such dock levelers utilize a lip pivotally fixed to the front edge of the ramp wherein the pivot axis of the lip is set outwardly, or forwardly, a substantial distance from the rear edge of the lip. Such a design allows the rear section of the lip between the pivot axis and the lip rear edge to project above the ramp surface and form a barrier when the lip is not in its fully extended cantilevered position. When such a lip is in positions between the stored depending position and the fully extended cantilevered position, the rear section of the lip still forms a barrier by projecting angularly to a varying degree above the ramp surface. Thus, the continued projection of the lip rear section might seriously obstruct loading and unloading operations. Another type of dock leveler having an automatic vehicle barrier is disclosed in US-A-4,920,598 representing the closest prior art and thus being the base for the above referenced preamble of claim 1. The dock leveler assembly disclosed therein relies on a portion of the lip to form a barrier. There are circumstances where it is desirable to provide an automatic barrier to prevent accidental material handling equipment runoff when the dock leveler assembly is in a stored cross-traffic position and loading and unloading equipment is being utilized. Such circumstances include situations where material must be loaded onto or unloaded from the extreme rear of the bed of the vehicle parked adjacent the loading dock and the placement of the material interferes with the use of the dock leveler with the lip thereof in a fully extended position resting on the rear of the vehicle bed. It is also advantageous to avoid the pinching area developed in levelers which utilize a lip having a barrier forming rear section which overlaps the ramp under certain operating conditions since a potential for entrapping equipment or personnel exists in such levelers. Thus, it is a general object of the present invention to provide an improved loading dock leveler which automatically raises a substantial safety barrier or stop to prevent fork lift trucks and related material handling equipment from accidentally running off the front end of the loading ramp when the latter is in a stored position. This object according to the present invention is accomplished by means of a dock leveler of the type indicated above and being characterized by the features of the characterizing clause of claim 1. It is an advantage of the present invention that it provides an improved loading dock leveler which is readily operable and has maximum safeguards for the safety of loading dock personnel and equipment. It is a further advantage of the present invention that it provides an improved loading dock leveler which allows loading and unloading operations involving the rear bed portion of a parked vehicle. Further and additional objects and advantages will appear from the following description, accompanying drawings, and appended claims. In accordance with one embodiment of the invention, a dock leveler is provided having a ramp hingedly mounted to a frame mountable in a pit formed in a loading dock. The ramp is mounted for movement between a stored first position wherein an exposed upper surface of the ramp is substantially coplanar with the loading dock platform surface, an upwardly inclined second position, and a declining third position. Operatively connected to the front edge portion of the ramp is a lip which is movable between a depending position when the ramp is in the stored first position, and an outwardly extended cantilevered position. The dock leveler includes a barrier means movable between an operative mode and an inoperative mode in response to movement of the lip to and from the lip depending position. In the operative mode, a predetermined first surface segment of the barrier means projects above the upper surface of the ramp and forms a vehicle safety barrier of optimum height when the lip is in the depending position and the ramp is in the stored first position. In the inoperative mode, the predetermined first surface segment of the barrier means does not project above the ramp surface when the lip is in an outwardly extended cantilevered position. The barrier means may be movable to a second operative mode to project a substantial portion of the predetermined first surface segment above the ramp upper surface when the ramp is in a declining third position and the lip is in an intermediate depending position between the stored depending position and the outwardly extending cantilevered position. For a more complete understanding of the present invention reference should now be made to the accompanying drawings wherein: Fig. 1 is a side elevational view in partial cross section of one embodiment of the improved dock leveler showing the ramp thereof in the stored first position, the lip in the depending position, and the barrier means in an operative mode. Fig. 2 is similar to Fig. 1 but showing the ramp in a raised second position and the lip in a depending position. Fig. 3 is similar to Fig. 2 but showing the lip in the extended cantilevered position, and the barrier means in an inoperative mode. Fig. 4 is similar to Fig. 3 but shows the lip in the extended cantilevered position resting on the rear portion of a vehicle bed and the barrier means in an inoperative mode. Fig. 5 is similar to Fig. 1 but shows the lip in an intermediate depending position, the ramp in the declining third position, and the barrier means in a second operative mode. Fig. 6 is an enlarged fragmentary sectional view of the lip of Fig. 1 in the depending position and the barrier means thereof in the operative mode. Fig. 7 is similar to Fig. 6 but shows the lip in the extended cantilevered position and the barrier means in the inoperative mode. Fig. 8 is an enlarged fragmentary perspective view showing a second embodiment of the improved dock leveler, with the lip in a depending stored position and a barrier means in an operative mode. Fig. 9 is an enlarged fragmentary vertical sectional view taken along line 9-9 of Fig. 8 and showing the lip in the depending position, the barrier means in the operative mode, and a linkage means operatively connecting the barrier means to the lip. Fig. 10 is similar to Fig. 9 but shows the barrier means in the inoperative mode. Turning now to the drawings and more particularly to Fig. 1, one embodiment of the improved dock leveler assembly I is shown in a stored, or cross-traffic, position. The assembly includes a supporting frame 10 mountable within a pit, not shown, of conventional design formed in a loading dock and having an open front side at the upright front wall of the dock and an open top side at the horizontal platform surface of the dock. The frame 10 includes an upright rear section 10a positioned adjacent the pit rear wall. The rear edge portion of a substantially planar loading ramp 12 is hingedly connected at X to the upper end of the frame rear section 10a. The ramp 12 is sized to conform to the configuration of the pit open top side so that when the leveler is in the stored cross-traffic position, the ramp overlies and closes the open top side thereby allowing personnel and material handling equipment to move across the exposed surface of the ramp which is substantially coplanar with the dock platform surface. The ramp 12 includes a reinforcing header section 14 mounted on and depending from the front edge 12a of the ramp 12. A row of axially spaced hinge tubes 16 is affixed to the front surface of the header section 14 to provide a conventional mechanism for hingedly connecting an extension plate or lip 18 to the front edge portion 12a of the ramp. The width of the lip 18 is substantially equal to the width of the loading ramp 12. When the ramp is in the stored first position, the lip assumes a depending substantially vertical position. A pair of laterally spaced keeper brackets 20 are disposed outwardly from the front of the frame 10 along a cross support 10b disposed adjacent the open front side of the pit. The brackets 20 supportingly engage the lip lower edge 18a when the lip is in the depending position and the ramp is in the stored first position, as shown in Fig. 1. Each bracket 20 is provided with an upwardly facing notch or pocket 22 sized to accommodate the elongate edge 18a of the lip. When the dock leveler assembly is actuated, the ramp 12 is pivoted to an initial predetermined upwardly inclined second position, as shown in Figs. 2 and 3, and then pivoted downwardly to a position which is compatible with the height of the bed of a vehicle B parked at the loading dock, as shown in Fig. 4. When the ramp 12 is raised, the lip or plate 18 is also pivoted from the depending position to an outwardly extending cantilevered position, as shown in Figs. 3 and 4, to bridge the gap G between the vehicle bed B and the front edge of the ramp 12. It will be apparent that the dock leveler assembly can accommodate the loading and unloading of a variety of vehicles since the ramp is movable between a raised upwardly inclined, above dock level, second position (Figs. 2 and 3) and lowered declining, below dock level, third position (Fig. 5). The various mechanisms, including hydraulic cylinder and piston devices for affecting pivotal movement of the loading ramp 12 and the lip 18 are well known to those skilled in the art and thus, a description thereof is omitted. The improved dock leveler assembly I includes a plurality of laterally spaced barrier members 30 adjustably mounted on the front portion of the ramp 12 and aligned in substantially parallel relation to the rear hinge axis X of the ramp 12. The laterally spaced members 30 form a barrier moveable between an operative mode and an inoperative mode in response to movement of the lip 18, as will be described more fully hereinafter. Each member 30 is located in close proximity to the front edge 12a of the ramp. Each member 30 includes an end portion 32 with a predetermined first surface segment 32a which is adapted to project upwardly above the exposed surface of the ramp through an aligned opening 12b disposed proximate the front edge 12a of the ramp when the ramp is in the stored first position. Each member 30 also includes a second end segment 34 which extends through a corresponding opening 14a formed in the ramp header section 14 and is affixed by welding or the like, to the under surface C of the lip plate 18. The number of ramp openings 12b and the number of header section openings 14a correspond to the number of laterally spaced members 30. The improved dock leveler assembly, sized to conform to conventional loading dock pits, may include six members 30 spaced across the width of the assembly. Each, or at least one, member 30 includes a foot extension 36 which abuts the lower end of the ramp header section 14 when the lip 18 is in the outwardly extended cantilevered position, see Fig. 3. The foot extension 36 forms a closure for the loading ramp opening 12(b) when the ramp is in the stored cross-traffic first position thereby preventing equipment or debris from fouling or being trapped in the ramp openings. In accordance with the present invention, the barrier means functions between various modes to enhance the safety of loading and unloading operations. As illustrated in Fig. 1, the upwardly projecting end portions 32 of the barrier members 30 while in a first operative mode, prevent handling equipment from accidentally running off the ramp 12. When the ramp is in the stored cross-traffic first position the upwardly projecting first end portion 32 of each member is at optimum height whereby the wheels or lower bumpers of the material handling equipment ( e.g. , fork lift trucks, carts, and the like) are blocked thereby avoiding the hazard of the equipment being inadvertently pushed or driven off the front edge of the loading ramp. The first end portion 32 of each member when in the operative mode, has the curved rearwardly facing surface 32a which may be impacted by the material handling equipment located between the ramp front edge 12a and the ramp fringe axis X as seen in Figs 1 and 2. When a truck or trailer is backed in and parked adjacent the loading dock to be loaded or unloaded, the dock leveler assembly is actuated by well known mechanisms to pivotally raise the loading ramp 12 to a predetermined upwardly inclined second position, as shown in Fig. 2. Raising of the ramp 12 to such a position frees the elongate edge 18a of the lip 18 from the keeper brackets 20 and allows the lip 18 to be pivoted by a conventional mechanism to an outwardly extended cantilevered position as shown in Fig. 3. Movement of the lip 18 from the depending position to the cantilevered position automatically lowers the barrier members to an inoperative mode wherein no portion of a spaced member 30 projects above the exposed surface of the ramp 12, as shown in Fig. 3. Once the barrier members are in an inoperative mode and the lip 18 is in the cantilevered position, the ramp 12 is then pivoted downwardly until the edge 18a of the lip rests upon the bed B of the parked vehicle, as illustrated in Fig. 4. The parked vehicle may then be loaded or unloaded safely. It should be noted that, in the inoperative mode, a top exterior surface 32b of end portion 32 of each laterally spaced member 30 is positioned in a coplanar relationship with the exposed surface of the ramp 12 and forms a closure for the aligned ramp opening 12b. The closure provided by the top surface 32b prevents equipment or debris from fouling or being entrapped in the ramp opening 12b during loading and unloading operations. After loading or unloading operations are complete, the assembly may be returned to the stored cross-traffic first position by simply reversing the sequence described above. Thus, the ramp 12 with the lip 18 in the extended cantilevered position is raised to a predetermined upwardly inclined second position, as shown in Fig. 3. Next, the lip 18 is pivoted to the depending position, as shown in Fig. 2, thereby automatically causing the end portion 32 of each laterally spaced member 30 to project through the corresponding ramp opening 12b and above the exposed surface of the ramp 12. The ramp 12 is then pivoted downwardly until the lip edge 18a engages the keeper brackets 20 thereby supporting the assembly in the stored first position. Referring to Fig. 5, it will be noted that the improved dock leveler assembly allows loading and unloading of the extreme rear portion of a vehicle bed under circumstances where placement of a load on the bed rear portion or removal of a load therefrom would interfere with the use of the assembly when the lip is in a fully extended cantilevered position. For this type of loading and unloading operation, the dock leveler assembly is raised to the upwardly inclined second position, as shown in Fig. 2, so that the lip 18 will clear the keeper brackets 20. The lip 18 is then pivoted outwardly to an intermediate depending position in order to allow the lip 18 to slide past the keeper brackets 20 when the ramp 12 is lowered to a predetermined declining third position, as shown in Fig. 5. Such a maneuver is commonly performed with existing dock levelers. Since the lip 18 is in an intermediate depending position, rather than the fully extended cantilevered position, a substantial portion of the end portion 32 of each laterally spaced member 30 will project through the ramp opening 12(b) and extend above the exposed surface of the ramp whereby the barrier is in a second operative mode. However, the spacing between members 30 is sufficiently wide to allow the tines of a fork-lift truck to pass between adjacent members 30 and thus perform loading or unloading operations at the rear of the vehicle bed; yet the spacing is sufficiently narrow to present a barrier or stop preventing passage therepast of the entire fork-lift truck. It will be seen that the improved assembly enhances safety since the upwardly projecting members 30 even when disposed in the second operative mode will still prevent accidental material handling equipment run off if loading dock personnel fail to return the assembly to the full stored cross-traffic position after the vehicle has been driven away from the dock. Any operator backing a fork-lift truck on the unstored declining ramp will encounter the barrier members if the truck is inadvertently backed too far towards the front edge of the ramp. A second embodiment of the improved dock leveler assembly II is illustrated in Figs. 8-10. The assembly includes a plurality (e.g. six) of generally L-shaped members 130 spaced laterally across the width of the front portion of the ramp 112 and mounted to pivot about a common axis. The pivotal axis is substantially parallel to the hinge axis of the ramp. The L-shaped members 130 are preferably arranged in two sets with one set being disposed on each side of the longitudinal centerline of the ramp 112. Each set may consist of three members 130 which are interconnected by a rod 138 passing through the central region of each member 130. A locking pin or key 138a is fitted in a keyway formed in part in each member 130 and the rod 138 thereby effecting uniform rotational movement of the members of a set about the rod axis. The rod 138 of each set is journalled within bores formed in brackets, not shown, affixed to the underside of the ramp. When the assembly is stored in the cross-traffic position, a first leg or segment 132 of each member projects upwardly to the optimum height above the exposed ramp surface through an aligned opening 112b which is proximate to, but recessed from the front edge of the ramp, as shown in Figs. 8 and 9. In assembly II a linkage means L is provided to operatively connect the lip 118 to the sets of barrier members so as to automatically move the latter between operative and inoperative modes in response to movement of the lip 118. An elongate transversely extending bracket 140 is fixedly mounted on the concealed surface C of the lip 118 and, when the lip 118 is in the stored mode, see Fig. 9, extends through an opening 114a formed in a depending reinforcing header 114 located at the outer, or front, edge of the ramp. One end of a link piece 142 is pivotally connected to the distal end of bracket 140 by a pin 144 and a second, or opposite, end of the link piece 142 is pivotally connected by pin 146 to a second leg 134 of the aligned generally L-shaped member 130. As a consequence of the operative connection between the lip 118 and one member of each set, movement of the lip 118 to the depending position will simultaneously raise the first leg 132 of each member 130 of the set to a first operative mode (thereby effecting) whereby a predetermined first surface 132a thereof, see Fig. 9, effects a vehicle safety barrier of optimum height, as shown in Figs. 8 and 9. On the other hand, movement of the lip 118 to the extended cantilevered position will simultaneously lower the first leg 132 of each member of the set to an inoperative mode wherein no portion of any of the members will project above the surface of the ramp, as shown in Fig. 10. In the illustrated embodiment II there is preferably a bracket 140 and link piece 142 for each set of barrier members. The barrier members may assume a second operative mode wherein a substantial portion of the first surface segment 132a of each member 130 projects above the ramp surface forming a vehicle barrier, when the lip 118 is moved to an intermediate depending position, such as previously described with regard to Fig. 5. Thus, loading and unloading operations involving the extreme rear portion of a vehicle bed may be readily performed with assembly II. It is to be noted that assembly II requires only two openings in the ramp header section 114. The brackets and associated link pieces are preferably mounted proximate the side edge portions of the lip and ramp as shown in Fig. 8. As in the case of the first assembly I, a surface 132b of each member first leg 132 is sized to provide a closure for the ramp openings 112b when the lip is in the extended cantilevered position, see Fig. 10. The first legs 132 also include the surface segments 132a which are substantially curved for engagement by the loading and unloading equipment as heretofore described. Since it may be desirable to replace individual L-shaped members 130 from time to time, an alternate manner of interconnecting each set of members is provided wherein, instead of the single rod 138 for each set, each member 130 in a set may be provided with a short shaft passing through the central region of the member, and each pair of adjoining shafts may be accommodated by a short tube disposed between a pair of members. Suitable locking keys fitted in keyways formed between each member, tube, and shaft can be used to effect uniform rotatational movement. Thus, an improved loading dock leveler assembly has been disclosed that automatically raises a substantial barrier in response to the movement of the lip to prevent material handling equipment from accidentally running off the front end of a loading dock.

Claims: A dock leveler (1) for a loading dock having a substantially horizontal platform surface, said dock leveler comprising: a frame (10) having a rear section (10a); a ramp (12) having a rear edge portion hingedly connected to the frame rear section (10a), said ramp (12) being movable between a stored substantially horizontal first position and a predetermined upwardly inclined second position; a lip (18) operatively connected to a front edge portion of the ramp (12) and movable between a stored position and an outwardly extended cantilevered position when said ramp (12) assumes said second position; and barrier means (30) movable between an operative mode and an inoperative mode, said barrier means (30) being in an operative mode when said ramp (12) is in the first position and said lip (18) is in the stored position, whereby a predetermined first segment (32) of said barrier means (30) extends through an opening formed in said ramp (12) and projects above the exposed surface of the ramp (12) and forms a safety barrier, while when said barrier means (30) is in an inoperative mode the predetermined first segment (32) thereof assumes a non-projecting position relative to the exposed surface of the ramp, said barrier means (30) being in said inoperative mode when said lip (18) is in the outwardly extended cantilevered postion, characterized in that the barrier means (30) is operatively connected to a concealed surface (c) of said lip (18). The dock leveler of claim 1 wherein the barrier means includes a plurality of laterally spaced members (30), one end (32) of each member (30) being disposed through a corresponding opening formed in said ramp (12) and projecting upwardly above the ramp exposed surface when said barrier means is in the operative mode. The dock leveler of claim 1 wherein each of said members (130) has a second section (134) extending angularly from said first section (132) and wherein actuating means (L) are operatively connected to said lip (118) and the second section of at least one member (130) for simultaneously effecting movement of said members (130) to said operative mode. The dock leveler of one of claims 1 to 3 wherein said lip (18) is movable into a stored position which regarding the lip (18) is a depending position for maintaining said ramp (12) in said first position and wherein said barrier means (30) is movable between said operative mode and said inoperative mode in response to movement of said lip (18) to and from the depending position. The dock leveler of claim 4 wherein actuating means (L) are provided which are reponsive to movement of said lip (18) for raising said barrier means (130) to an operative mode when said lip (118) is moved to the depending position and for lowering the barrier means (130) to its inoperative mode when said lip (118) is moved to the outwardly extended cantilevered position. The dock leveler of one of claims 1 to 5 for mounting within a pit formed in said loading dock, the pit having an open front side at an upright front wall of the loading dock and an open top side at a substantially horizontal platform surface of the dock, said dock leveler comprising: said frame (10) mountable within said pit and having a rear section (10a) thereof positionable adjacent the rear wall of the pit; said ramp (12) having its rear edge portion hingedly connected to the frame rear section (10a), said ramp (12) being movable between a start substantially horizontal first position overlying the pit open top side and having an exposed surface of the ramp (12) substantially coplanar with the dock platform surface and said predetermined upwardly inclined second position; said lip (18) operatively connected to the front edge portion of the ramp (12) and movable between said stored depending position and said predetermined upwardly inclined second position; and said barrier means (30) operatively connected to said lip and activated thereby between said inoperative mode and a first operative mode; said barrier means (30) being in said first operative mode when said ramp (12) assumes the first position and the lip is in the depending position whereby a first segment (32) of said barrier means (30) is exposed and projects a first predetermined distance above the ramp exposed surface and formes a safety barrier; said barrier means being in its inoperative mode wherein no segment thereof projects above the ramp exposed surface when said lip (18) is in said outwardly extended cantilevered position; said dock leveler being characterized in that said ramp (12) has a predetermined declining third position; that said lip has an intermediate depending position and that said barrier means is operatively connected to said lip (18) and activated thereby between said first operative mode, said inoperative mode and an additional second operative mode, so that said barrier means (30) is in the second operative mode when the ramp (12) assumes the third position and said lip (18) is in said intermediate depending position, whereby only a portion of the first segment of the barrier means (30) is exposed and projects a second predetermined distance above the exposed surface of the ramp (12) and forms thereby a safety barrier. The dock leveler of claim 6 wherein the barrier means (30) includes a second segment (34) spaced from said first segment (32) and operatively connected to a concealed surface of said lip (18). The dock leveler of claim 1 wherein the barrier means (30) includes a plurality of members (30) relatively spaced across a front portion of said ramp (12), one end (22) of each member projecting upwardly through an aligned opening formed in said ramp (12) above the ramp exposed surface when said barrier means (30) is in either the first or second operative mode; at least one member (30) having a second end (34) attached to a concealed surface of said lip (18). The dock leveler of claim 6 wherein the barrier means (130) includes a plurality of laterally spaced members (130), each having a first section (132) projecting upwardly through an aligned opening formed in said ramp (112) when said barrier means (130) is in either the first or second operative mode, and a second section (134) spaced from said first section (132); and linkage means (L) for operatively interconnecting said lip (118) and the second section (134) of at least one member (130). The dock leveler of claim 9 wherein said linkage means (L) includes a bracket (140) affixed to a concealed surface of said lip (118) and a link (142) having one end connected to said bracket (134) of the said one member (130). The dock leveler of claim 6 wherein the barrier means (30, 130) is disposed in close proximity to, but spaced from, a front edge portion of the ramp (12, 112). The dock leveler of claim 6 wherein said frame (10) includes a front section (10b) positionable on a bottom wall of the pit and adjacent the pit open front side, said frame front section (10b) being provided with outwardly extending retaining means (20) for supportingly engaging said lip (18, 118) when said lip is in the depending position. The dock leveler of claim 6 wherein said barrier means (30, 130), when in the operative mode, is disposed in spaced substantially parallel relation with the hinge axis (X) of said ramp (12, 112). The dock leveler of claim 6 wherein the barrier mens (30, 130), when in the operative mode, includes a substantially curved, rearwardly facing surface (32a, 132a). The dock leveler of claim 8, wherein the barrier means (30, 130) includes a substantially planar top surface (32b, 132b) disposed in substantially coplanar relation with the ramp exposed surface when said barrier means (30, 130) is in an inoperative mode. The dock leveler of claim 8, wherein each member of the barrier means (30) is provided with a foot extension (36) disposed intermediate said first and second segments (32, 34) and effecting closure of the aligned ramp opening when said member (30) is in the first operative mode.

Inventors: HAHN NORBERT, SWESSEL MICHAEL A, HAHN, NORBERT, SWESSEL, MICHAEL A.
Applicants: RITE HITE CORP, RITE-HITE CORPORATION
Application year: 1991
Main classification: B65G69
IPC codes: B65G69