A particular application of the invention is in ambulances, in which a patient on a wheeled stretcher, or an infant in an incubator, is required to be brought into the ambulance for transportation to a treatment centre, and must be taken out of the ambulance on arrival. Since the floor inside the ambulance is spaced at a height above the ground surface, the patient and stretcher must generally the lifted into the vehicle.

In our published UK patent application 2366782 there is described a load handling system for a vehicle wherein a wheeled load is moved onto a horizontal load bed of the vehicle by means of a ramp surface, with an actuator being provided to propel a shuttle along the load bed and

the ramp surface. The shuttle is attachable to the load to urge the load into or out of the vehicle.

An object of the present invention is to provide a simple and effective means for attaching a wheeled load such as for example, a stretcher, a wheelchair or an incubator to a movable actuator.

The actuator of the load handling system preferably comprises a first elongated track portion extending substantially in the plane of the load bed, and having a second track portion extending across the ramp surface in alignment with the first track portion. A shuttle or follower is mounted to the track so as to be movable from a position within the load bed to a position adjacent the end of the ramp surface remote from the load bed. The follower is provided with an engagement means cooperable with the load, for releaseably securing the load to the follower.

In one embodiment, the attachment means comprises an upwardly-open hook pivotable about a horizontal axis and biassed toward a raised position, and a locking element movable relative to the hook between a locking position and a release position, and biased towards the locking

position wherein the locking element prevents disengagement of the hook from a load.

An embodiment of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a vehicle load bed and a ramp surface, in side view with the ramp surface in the stowed position; -Figure 2 is a view similar to figure 1, showing the ramp surface in a first partially-deployed position; Figure 3 is a view similar to figures 1 and 2, showing the ramp surface in a second partially-deployed position; Figure 4 is a view similar to figures 1 to 3, showing the ramp surface in the deployed position; Figure 5 is a schematic side view of an attachment device for attaching a load to a follower; Figure 6 is a view similar to Figure 5 showing the attachment device secured to a load;

Figure 7 is a side view of the device pushing a load; Figure 8 is a side view of the device just before disengagement; and Figure 9 shows the device disengaged from the load.

In the preferred embodiment, the load handling device consists of a shuttle 20, which is restrained in a guide track 4, and is moved along the track 4 by a drive system. The stretcher, wheelchair or other load is connected to the shuttle by an attachment device and is drawn into/out of the vehicle by moving the shuttle 2-0 along the track 4.

The general arrangement of the track is seen in Figures 1 to 4. The track 4 extends along the load bed 3 of a vehicle, and may continue along a ramp 5,8 pivotally attached to the vehicle at the rear of the load bed 3.

A belt drive is contained within the track 4. The belt is preferably a single length of flexible webbing, with its ends joined to the shuttle 20. A clamp arrangement at this point allows the effective belt length to be set during installation and for adjustment in service to remove of excessive slack. However, other belt tension adjustments will be apparent to those skilled in the art.

The belt may consist of vehicle seat-belt type material.

The belt runs forward and aft from the shuttle and passes over a low-friction bearing at each end of the track.

After passing over the end bearings, the belt returns along the track and passes underneath the shuttle.

At a point along the track 4 below the load bed 3 of the vehicle, the belt passes into a motor box 9, where it is guided onto a drive spool 10. The drive spool 10 is mounted on a motor driven drive shaft (in this instance, the motor-gearbox output shaft) and the belt is pinched onto the spool by spring loaded contact rollers (not shown) in order to generate sufficient contact friction to drive the belt. The degree of pinch is preferably adjusted so that the belt slips at peak rated motor torque, so that slipping occurs at the extremes of shuttle travel and if the shuttle senses an obstruction.

The towing mechanism is seen in Figures 5 to 9, and consists of two main parts, the stretcher or load attachment and the capture mechanism assembly. While the embodiment will be described with reference to a stretcher, the load may alternatively be a wheelchair, an incubator, or any other wheeled load.

The stretcher shown in part in the Figures comprises a bed, four legs 15 and castors 12 at the ends of the legs 15. Fixed to the structure of the stretcher, an attachment provides a means by which a capture mechanism mounted to the shuttle 20 can attach to the stretcher in order to transport it in or out of the vehicle.

The stretcher attachment comprises a horizontal bar 11 which is engageable with the capture mechanism. The horizontal bar is set at approximately the axle height of the stretcher castors 12, and may be mounted to the stretcher by any convenient means such as welding, screw fasteners, mounting brackets or the like.

The capture mechanism is connected to the shuttle through a slot in the track, and is fixed to the shuttle 20.

A bolt 16 fixed to through the shuttle acts as the pivot bar for the capture mechanism.

The capture mechanism comprises a hook bar 13 and a locking bar 14, both of which are supported on a pivot bolt 16. The hook bar 13 has a hooked end 13b at its left-hand end, and is weighted on the right-hand side (as seen in the Figures) so that it tends to pivot clockwise under its self-weight to lift the hooked end 13b. A

vertically extending slot 13a is formed in the central region of the hook bar 13, through which slot the pivot bolt 16 extends. Rollers 13e support the heavier (right) end to prevent contact between the hook bar 13 and the floor of the vehicle.

The locking bar 14 extends in parallel to the hook bar 13, and is movable relative thereto between a raised position and a lowered position by pivoting about the pivot pin 16. In the raised position, an end surface 14a of the locking bar obstructs the entrance of the hooked end 13b. Blocks on the hook bar engage stops on the locking bar to limit the relative rotation of the two bars 13 and 14. The locking bar 14 is counter weighted to urge the end surface 14a to a raised position, to ensure it keeps the horizontal bar of the stretcher attachment trapped.

As seen in Figure 5, the device is at the lower end of the ramp 8, at its limit of travel. The roller 13e of the hook bar 13 is lifted by a cam 17 on or adjacent the track to tilt the hook bar so that the hooked end 13b may pass beneath the horizontal bar 11 on a stretcher. To connect the stretcher, the stretcher is rolled toward the hook bar 13 in the direction of arrow A, until the bar

11 passes over the hooked end 13b and contacts a stop surface 13d adjacent the pivot pin 16. Movement of the stretcher is arrested by the stop surface 13d and by the stretcher wheels reaching the end of the ramp. The orientation of the castors is such that the castor wheel 12 is on the ground and the bar 11 is above the ramp when contact is made between the bar 11 and the stop 13d.

The drive mechanism is then started and the hook bar 13 begins to move up the ramp 8. As the roller 13e moves off the cam, the hooked end 13b swings upwards and, after a predetermined movement, engages the bar 11. During this predetermined movement, the locking bar 14 is held down by the bar 11 until the bar 11 enters the hooked end 13b of the hook bar. The locking bar 14 then swings upward and its end surface 14a traps the bar 11 in the hooked end 13b.

The drive mechanism continues to draw the stretcher up the ramp and into the vehicle until it is fully inside the vehicle.

When the stretcher has reached the desired position, the operator depresses the locking bar 14 with his foot and moves the stretcher slightly forward to disengage the

hooked end 13b from the bar 11. This action releases the stretcher so that it can be drawn forward, leaving the towing mechanism underneath. The stretcher can then be moved sideways to a final securing position in the vehicle.

To offload the stretcher, it is re-secured to the hook bar 13 by moving the stretcher rearwards over the hook bar 13. The bar 11 of the stretcher first depresses the locking bar 14, and then enters the hooked end 13b of the hook bar 13, whereupon the locking bar 14 rises to prevent disengagement. The drive mechanism is then started to move the stretcher out of the vehicle, the end surface 14a of the locking bar 14 pushing the stretcher while the hook bar 13 restrains the stretcher when it runs down the ramp 8, or if the vehicle is parked on a downslope. It is important to note that the castors of the stretcher will now face in the opposite direction from their orientation when the stretcher was loaded into the vehicle.

As the mechanism approaches the bottom of the ramp, seen in figure 8, the leading wheels of the stretcher level out on the ground, and the hooked end 13b of the hook bar 13 is raised by the bar 11 as the now trailing wheels of

the stretcher move down the ramp 8 and onto the ground due to the angle between the ramp and the ground. The hook bar is supported by the bar 11 and the roller, with the pivot pin 16 at the lower end of the slot 13a. The locking bar is moved to a lowered position by stops within the hook bar adjacent the roller 13e engaging the underside of the locking bar. The locking bar 14 remains in its lowered position relative to the hook bar while the hook bar is raised off the pivot pin 16, because the hook bar is raised whereas the pivot of the locking bar 14 is not a slot but a bore affording no radial movement to the locking bar.

The hook bar 13 then reaches the end of its travel, but due to the reversed orientation of the castors, the wheels 12 are closer to the ramp 8 than the bar 11. This raised positioning of the hook bar on its pivot pin 16 ensures that the locking bar is in its lowered position relative to the hook bar, and thus a slight forward movement of the stretcher (i. e. towards the ramp) can move the bar 11 out of the hooked end 13b of the hook bar 13. The hooked end 13b of the hook bar 13 then falls so that the hook bar is again supported by the roller and the pivot pin 16, which returns to the top end of slot 13a, seen in Figure 9. The stretcher can then be rolled

away from the ramp 8 and over the hook bar 13, since the bar 11 passes over the hooked end of the hook bar 13 while the castor wheels 12 are on the ground.

While the hook bar and locking bar in this embodiment are rotated by their self weight, it is contemplated that in alternative embodiments resilient means such as springs may urge the bars to their required positions, and separate cam means may be provided to control the movements of the hook and locking bars. It has been found that due to the angle between the ramp and the ground, and the inevitable step at the end of the ramp, the cam 17 may be omitted, and the hooked end 13b of the hook bar may rest on the ground at its extended position.

A cam 17 may be provided at a point within the vehicle to lower the locking bar 14 relative to the hook bar 13 after the stretcher is within the vehicle, so that the stretcher may be disengaged from the hook bar.

The hook bar may be provided with a cam plate 21, seen in Figure 9 extending down and away from the upper edge of the hooked end 13b of the hook arm 13. The function of the cam plate 21 is to reconnect the stretcher to the hook arm when the stretcher is within the vehicle. To

reconnect, the bar 11 of the stretcher is placed in alignment with the track, and the hook bar 13 is driven backwards in the vehicle towards the bar 11. The cam plate 21 engages the bar 11 and rotates the hook bar 13 so that the hooked end 13b passes beneath the bar 11.

The balance of the hook bar then raises the hooked end 13b behind the bar 11, with the locking bar 14 held down by its engagement with the bar 11. A small forward movement of the hook bar 13 engages the bar 11 in the hooked end 13b, and allows the locking bar 14 to rotate to the locking position.

In the absence of cam plate 21, the locking and hook bars may be depressed by an operator to pass backwardly beneath the bar 11 during the reconnection operation.

In a further alternative, the track may extend only along the loadbed of the vehicle, and the ramp may be omitted.

Such an arrangement may be used to draw a stretcher having a foldable undercarriage into an ambulance. In such an arrangement, coupling the stretcher to the attachment device is facilitated by the provision of the cam plate 21.