• DEMOUNTABLE DISTRIBUTION 13
Page 56
Page 57
If you've noticed an error in this article please click here to report it so we can fix it.
by Alan Bunting, MIMechE
This final week: the Multiloader equipment marketed by Mukicargo Systems Ltd, Atbion Industrial Estate, West Bromwich, Site's., as used by G. and R. Lee (Cktverley) Ltd, of Claverley, Shropshire.
Body swop test
A large number of companies in Scandinavia produce specialized vehicle equipment and load-handling units, and one of the most active in Britain is the Finnish Autolava concern whose roll-on troll-off machines have been manufactured here for three or four years. Recently, the closely related Multiloader support-leg demountable gear has been introduced to the British market. This is more applicable to the general distributive trades, and it forms the subject of this CM appraisal.
In its principle of operation the Multiloader system is unlike any of its rivals on the British market. A hydraulic motor is built into a lifting hinged cradle at the rear of the chassis. It drives a pair of serrated rollers which "drive" the body forward and back through contact with the underside of the floor runners. The runners are simple steel channels but there was no hint of slipping between the rollers and runners during our test, despite their having been greased inadvertently.
Two simple free-wheeling rollers on the front of the body allow it to move freely when the cradle has raised the runners clear of the chassis farther back.
As with the Multilift equipment, the body is raised and lowered through a see-saw action — a point of balance being reached when the body tips back during demounting, on to its rear legs, and tips forward when picking-up to bring the runners on to the chassis. At first sight this appears to he a particularly unscientific operation, the whole body and its load (which could weigh up to 16 tons with the base unit tested) being poised momentarily at its centre of gravity, on the drive rollers. But the length of support leg is chosen to match both the chassis frame height and the rear suspension stiffness, so that when fully laden the drop at front or rear end as the body moves "over centre" is limited to an inch or two. On the other hand, with the body on the test vehicle unladen, there was a clearance of about 8in. below the rear legs.
A skilled driver can, however, adjust the ' height of the cradle so that the drop height is minimal, and it is worth recording that G. and R. Lee includes eggs among the farm produce carried in its demountable bodies, and •in two months of operation no breakages have been attributed to shock loadings as the body "overbalances".
Demounting procedure involves initially folding down all four support legs. They are of exceptionally robust construction, the rear pair braced on a longitudinal hinge-line which effectively resists the fore-and-aft forces imposed on the rear legs as the body and chassis are "driven apart" by the serrated rollers. The rear body locks are then released by a fifth-wheel coupling type of pull-lever on the nearside; the locking tongues are stout rectangular pieces normally spring-loaded outwards from the chassis rail flanges. A direct connection with the release mechanism operates a cut-off valve, immobilizing the hydraulic motor drive when the rear locks are engaged. At the front of the body, the legs are pulled out about 5in. before being hinged down from their stowed position. The leg hinge-pin extends inboard to incorporate a second pair of locks, locating in elongated sockets in the "buffers" with which the front of the body makes contact when drawn fully on to the chassis.
With the legs lowered and the locks released, the rear cradle is lifted and the body "motored" rearwards until it, literally, overbalances. A drawback here is that td position the body precisely on the ground, against a loading bank for example, involves a lot of trial and error — moving the vehicle back or forward and finding how far the body must be moved before it drops (depending on its load distribution).
After the rear legs have contacted the ground, the vehicle handbrake 1.nust be released. The body then stays put, the hydraulic drive being reacted by the chassis rolling forward. If the body is lightly loaded or the whole exercise is being carried out facing up a slope, then the rear legs, not surprisingly, tend to slide along the ground.
Unless the driver is utterly ruthless in failing to control the speed of the hydraulic motor as the drive rollers reach the front end of the body, there is little risk of the body crashing to the floor. The serrated drive rollers merely contact the front body rollers and "free-wheel". There could, however, be a nose-dive risk with the chassis — handbrake off — facing down a slope.
The front of the body is finally lowered with the cradle, leaving the chassis to drive away. Lee's drivers, in practice, chock the rear wheels with bricks so that the
handbrake can remain off for the whole demount and pick-up operation.
Picking up the Multiloader body involves aligning the two pairs of rollers to within an accuracy of one or two inches transversely. This is not difficult in practice as the driver has a clear view through his cab rear, window. However, Lee's drivers are briefed to get out of the cab and walk back to check the alignment before raising the front of the body with the drive roller cradle. As the body is drawn forward reasonable care has to be taken to see that when it reaches the balance point its front runners drop outside the chassis rail guide flanges.
One of the Multiloader's particular attractions is the low loading height possible with a demounted body. On Lee's Ford D900 chassis the floor height is 4ft 9in.; with the body on its support legs the floor comes down to only 4ft lin. above ground level.
Test timings showed that an 18ft body with about 6 tons on board could be demounted surprisingly quickly — in 1min 50sec. It was picked up again in 2min 5sec, which included a double attempt in getting the front of the body up to its "buffers".
Because the Multiloader gear is robust, it is also heavy — adding about I4cwt to the tare weight. The quality of the equipment is also reflected in its price, so that in capital cost and load penalty terms it could probably be justified only on chassis of, say, 8 tons capacity upwards. Its upper weight limit would, however, make it suitable for use on the heaviest six-wheeled chassis.
Service experience Robert Lee, one of the directors of the company operating the Multiloader vehicle, explained how he has been able to replace two fixed bodied vans with one chassis working with two bodies. The pattern of operation at present involves loading farm produce — which can include potatoes, onions. eggs and other seasonal vegetables — at the main farm collection point at Claverley. Produce is being brought in by farm trailer all through the day, so that the parked body can be loaded over a seven or eight-hour period. Damage through dumping produce on the ground is avoided, as well as the double-handling implied.
In the meantime the other body is on the chassis, delivering the previous day's "accumulated produce" to Dudley market some 10 miles away and to Lee's two retail shops.
Mr Lee was enthusiastic about the system's simplicity from the driver's point of view. Returning to a bleak exposed farmyard late on a winter's night, the driver can drop his empty body, load the waiting loaded body and be away — all in 10 minutes at the outside.