[0001] The invention relates to load handling vehicles of the kind which have a fixed load
supporting platform and a lifting mast mounted on a carrier for traversing movement
within the platform. In such vehicles a well is formed in the load supporting platform
and the carrier is supported on rollers which run in C-shaped load-bearing channels
mounted facing each other on either side of the well. Vehicles of this kind are generally
known as Side-Lift Trucks.
[0002] Lateral guidance of the carrier in known vehicles is by means of side thrust rollers
mounted on either side of the carrier and running on the vertical faces of the load-bearing
channels. In order to minimise 'walking' and jamming of the carrier it is necessary
for the mounts for the side thrust rollers to be carefully shimmed so that the desired
positioning of the side thrust rollers relative to the load supporting channels is
precisely achieved. This arrangement also requires great accuracy in the alignment
of the load bearing channels relative to one another.
[0003] The present invention does away with the need for conventional side thrust rollers
mounted on both sides of the carrier and provides an arrangement whereby all the guidance
of the carrier is tied to one side thereof and whereby the load bearing channels simply
provide support tracks for the carrier supporting rollers and play no part in the
lateral guidance of the carrier.
[0004] According to the present invention, there is provided a load handling vehicle comprising
a frame which provides a load supporting platform in which a well is formed,
a lifting mast,
a carrier on which the lifting mast is mounted for traversing movement of the platform
within the well,
a pair of horizontally extending C-shaped load-bearing channels mounted facing each
other one on either side of the well with their webs substantially vertical, and
carrier supporting rollers mounted on the carrier and running in the load-bearing
channels;
wherein the vehicle further comprises a horizontally extending C-shaped guide channel
mounted with its web substantially horizontal adjacent one of the load-bearing channels
and parallel thereto, and at least two guide rollers mounted on the carrier and running
in the guide channel.
[0005] Movement of the carrier in one known vehicle of the type described is by means of
hydraulic cylinders connected between the vehicle frame and the carrier. Such arrangements
have inherent faults such as undesirable 'walking' effects, slewing and jamming of
the mast and dangerous load swing. Other systems use hydraulic motors instead of cylinders
and use chains to drive the carrier; these systems suffer from problems of excessive
hydraulic flow demand, lack of power for straightening loads, and complexity of maintenance
and service of the motor itself.
[0006] According to a preferred feature of the invention, the carrier is moved by at least
one extensible cylinder connected between the carrier and the frame and extending
diagonally across the well. Preferably, a pair of such cylinders are provided connected
one on each side of the carrier.
[0007] Such an arrangement of cylinders has been found to work very well with the carrier
guidance arrangement provided by the present invention to provide a lifting vehicle
in which the carrier can be smoothly and controllably moved across the platform without
the disadvantages exhibited by prior arrangements.
[0008] An embodiment of the invention is described below with reference to the accompanying
drawings in which:
FIGURE 1 is a diagrammatic plan view of part of a load handling vehicle; and
FIGURE 2 is a diagrammatic side view looking along the line of arrow A in Figure 1.
[0009] Figure 1 shows part of a Side-Lift Truck having a main frame provided mainly by a
number of beams 1, 2, 3, 4, 5. The frame provides a flat load supporting platform
6 having a central well 7 formed therein. Mounted on the frame beams 1 and 2 on either
side of the well are a pair of horizontally extending C-shaped load-bearing channels
9 and 10; the webs 11, 12 of the channels being substantially vertical.
[0010] A carrier 13 is mounted for traversing movement of the platform and is supported
on rollers 14 which run on the lower horizontal flanges 15 of the channels 11, 12.
It will be understood that the carrier supports an extensible mast for lifting and
carrying loads; only the uprights 16 of the mast being shown in the drawings. The
rollers 14 are mounted on lateral members 17, 18 of the carrier.
[0011] On one side of the well, a horizontally extending C-shaped guide channel 19 is mounted,
with its web 20 substantially horizontal, adjacent the respective load-bearing channel
11. A pair of guide rollers 21 are mounted on the carrier 13 by means of a bracket
22. The rollers 21 are mounted to run in the guide channel 19 with a small clearance
between the outer surface of the roller and the flanges 23 of the guide channel.
[0012] Correct positioning of the guide rollers 21 in the guide channel 19 can be achieved
by vertical and horizontal adjustment of the bracket 22 such as by shimming. The inner
surfaces of the flanges 23 may flare slightly such that the clearance between those
surfaces and the guide roller can be adjusted by vertical movement of the guide roller.
[0013] Movement of the carrier along the channels 9 and 10 is effected by a pair of hydraulic
cylinders 24 coupled between the carrier and the vehicle frame.
[0014] Guidance of the carrier is thus carried out only on one side thereof and the load-bearing
channels simply provide support tracks for the rollers 14 by means of their lower
flanges 15 and play no part in the lateral guidance of the carrier.
1. A load handling vehicle comprising
a frame which provides a load supporting platform in which a well is formed,
a lifting mast,
a carrier on which the lifting mast is mounted for traversing movement of the platform
within the well,
a pair of horizontally extending C-shaped load-bearing channels mounted facing each
other one on either side of the well with their webs substantially vertical, and
carrier supporting rollers mounted on the carrier and running in the load-bearing
channels;
wherein the vehicle further comprises a horizontally extending C-shaped guide channel
mounted with its web substantially horizontal adjacent one of the load-bearing channels
and parallel thereto, and at least two guide rollers mounted on the carrier and running
in the guide channel.
2. A load handling vehicle as claimed in claim 1 wherein at least one extensible cylinder
is provided for moving the carrier along the load-bearing channels; the cylinder being
connected between the carrier and the frame and extending diagonally across the well.
3. A load handling vehicle as claimed in claim 2 wherein a pair of such cylinders
are provided connected one on each side of the carrier.
4. A load handling vehicle as claimed in any preceding claim wherein the guide rollers
are mounted on the carrier with means for adjustment vertically and laterally of the
carrier.