PUSHING FOR BUSINESS
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• Registrations of tipper chassis are more depressed than in any other sector of what is an acutely suffering truck market. The usual winter seasonal dip in tipper sales has been given an even crueller edge by the recession. Not surprisingly, demand for hydraulic tipping gears has dropped accordingly.
Edbro, the traditional UK market leader, has reported an 85% fall in profits, while its main domestic competitor Telehoist has suffered a long break in ram production caused by the transfer of manufacturing from its Cheltenham home to the Alcester factory of its parent Warwick Hydraulics group.
York Trailer's TEC Hydraulics (formerly Carrimore) subsidiary has been quietly sold to Hyva. further consolidating this Dutch Company's position in the UK market.
Radial clearance between adjacent ram tubes in the original Crown gears — ball joint at the body attachment — was so tight that slight bending brought scuffing tube-to-tube contact. As displacement gears rely for their leaktightness on the outer machined surface, scuff damage was disastrous. Where more extreme bending was involved, ram seizure was induced.
A new range of rams has now been developed by Nummi, with the British market particularly in mind. They will be marketed this time under the Multilift name. Several prototypes are being evaluated in UK tipper fleets. They feature more generous tube-to-tube clearances, able to tolerate greater bending.
Established tipping gear market contenders have meanwhile been active in extending and improving their products. During 1990 Edbro launched improved versions of its DX displacement gears aimed primarily at the multi-wheeler market.
RAM NUTS
The lower stage, more highly-stressed, tubes now feature ram nuts which screw into the top of the tube in the usual way, but which are also a tight fit around the outside of the tube as well. There, each "overlap" nut provides extra radial support. during the kind of extreme bending which could otherwise lead to ovalling or even splitting of the tube end.
Another innovation on Edbro's DX rams concerns the top (outer) cover. It is now attached more rigidly — by three rather than one (central) bolt — to the top cap, better ensuring its axial alignment with the top stage tube, so reducing the risk of tube outer surfaces being scuffed, typically when the vehicle is being driven off a rough site before the body is lowered.
Body hinge brackets accompanying Edbro's latest DX gears incorporate non-metallic bushes which help reduce empty running clatter. They can also be replaced when worn. Most of the wear occurring, as Edbro points out, during rough road vibration and not while tipping.
Last year Edbro launched its 950-series nine-cylinder swash(or wobble-) plate pumps. They have larger diameter pistons than the old 400-series and the angle of the swash-plate has been increased from 14° tc 17°, so effectively lengthening the piston stroke. Maximum pressures and flow-rates arc up by a third to 200 bar and 72 litres/min, to cut tipping times by up to 50%.
Telehoist's main recent product update has been a better looking but no less robust version of its single pneumatic control valve, regulating power-take-off as well as tipping functions. It acts as a safeguard against the body being lowered while the PTO is still engaged. Protection of the PTO against foolish or careless drivers has also been a recent concern of Gravesend, Kent, based Stallion Hydraulics, whose main business involves the marketing of Italian Hydrocar tipper hydraulic equipment in Britain, but which nevertheless undertakes a certain amount of R&D in its own right.
Stallion's new £163 interlock switch, suitable for all makes and types of PTO, avoids gearbox damage without the previously associated safety risk of tapping into the vehicle's brake air supply. Instead the Stallion interlock switch uses a solenoid energised from the parking brake indicator lamp. As soon as the brake lever is released, the air II supply is cut off, disengaging the PTO.
Hytec Tippers, a small all-British company formed in the early '80s, has succeeded in attracting business from erstwhile Edbro and Telehoist customers running sixand eight-wheelers who find displacement gears unappealing because of their higher initial cost and more difficult servicing procedures.
Rams made by Hytec for multiwheelers, which accounts for the bulk of production, operate on the simpler bore seal principle, though using a novel form of rubber fabric seal construction which is claimed to improve seal effectiveness at lower pressures, making for dryer cylinders.
ANTI RATTLE
Last June Hytec started fitting all its rams with an anti rattle device consisting of a rubber extrusion wrapped around the bottom of the base tube. When the vehicle is travelling with the body down the ram outer cover makes contact with the rubber ring, preventing noise and wear resulting from metal-to-metal contact.
Drum Engineering, whose tipping division now operates from a separate factory in Leeds, has also remained loyal to traditional bore sealing, while seeking to emulate the durability and leaktightness of displacement rams. The latest two-part seal and bearing pack from Drum replaces the "bicycle pump" cup washer arrangement. The aim has been to prevent seepage of fluid past the seals when the ram is down which then becomes visible — notably to Dip inspectors — when the body is next tipped. At the same time those unpleasant build-ups of black sludge on top of the oil tank are avoided.
Two interconnected levers, one for tipping, the other for PTO engagement, are built into Drum's latest cab control assembly, which operates independently of the chassis air system.
Ultimate Hydraulics, importer of the unique American Harsh range of tipping gears, which effectively combine one, two or even three hydraulic rams into an underbody scissors-type stabiliser, last year added a number of new or revised models to its UK range, with more to come in 1991.
Managing director Grant Faulkner says that, notwithstanding the recession, some 500 Harsh sales were recorded in the UK in 1990— a small increase on 1989. New models include the little A5 gear for 3.5 tonnes gvw chassis.
For 17-tonners Harsh has designed the E55 gear (new for the US as well as for the UK) which uses one ram with more, but shorter stages than those of the twin rams in the established E50 model sold hitherto for heavy four-wheelers. Protrusion of the single ram below chassis frame level is reduced, to avoid propshaft clearance problems. The new E55 gear has a 20% greater lift capacity enabling it to suit longer (up to 6.1 m) bodies.
LONG PUSH
Another new Harsh model shortly to be introduced is the H80, for longer (up to 6.7m body length) and six-wheeler applications which, 'til now have had to be met by the much heavier and costlier K I 10 unit.
All Harsh gears are double acting — powered up and down for fast site turnround, Tip-and-lower times for the bigger (multi-wheeler) gears have now been reduced by another 25% thanks to increased flow through the spool of a revised Italian Lamborghini control valve and matching pipework.
0 by Alan Bunting