New Tipping Gear Reduces Body Height
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ATRIPLE-EXTEMION Telehoist ram, recently introduced by W. W. Jenkins (Cheltenham), Ltd., Swindon Lane, Cheltenham, enables the height of the underside of the body above the chassis to be considerably reduced. This represents a saving, in some cases, of 3-4 ins. in comparison with that required when a standard double-extension ram. is used.
The smallest triple-extension ram, the S.L. 10, which is capable of a 20-ton thrust, has a closed-centre measurement of about 20 ins, and an extension of 40 ins. It may be compared with the S.L,2 double-extension ram with a 10-ton thrust and a 36-in, extension, of which the closed-centre distance . is 28 ins.
Universal mountings are fitted at each end of the ram to obviate bending stresses. The base casting is provided with trunnion lugs which provide for longitudinal movement, and the side plates are pivoted in a sub-frame to give lateral swivelling. The eye of the inner tube is pinned to a box-type universal coupling.
Neoprene is used for the static outerring seals, and the piston-lip seals are secured in position by retaining spreader rings which are designed to obviate seal distortion. A felt retaining ring in the gland nut prevents the entry of dust and other foreign matter.
The ram is mounted on the sub-frame with the reservoir tank, and can be fitted to a chassis in a few hours. The average time taken to equip an S-type Bedford, including the fitting of frame, brackets and pump unit, and final testing, is four hours.
The gear pump is combined with the gearbox power take-off unit, and the drive gear is engaged with either the spur or helical layshaft gear by a lever in the cab. Of special interest is the announcement that a new oil is to be used, in place of engine oil, to prevent fluid foaming and metal corrosion. Its use will increase the rate of tip and reduce noise. The lower gear torque required will also lengthen the life of the pump.
A feature of the standard doubleextension rains is an outer container. formed by the casing, to which the oil is by-passed by means of an overriding device when the inner piston reaches the end of its travel. A relief valve is not, therefore, necessary.
Among the latest equipment to be developed by the concern is a 21-cubicyd. liquid-cement dumper body, operated by twin double-extension rams and fitted with an adjustable pan and chute. The angle of tip is 87 degrees, and discharge is controlled by a manually operated trap.
A swinging baffle in the body keeps the cement liquid when the vehicle is travelling, The chute may be traversed through 180 degrees and the angle with the ground is variable. It is fitted with counterbalance weights, and is tilted to a vertical position when not in use.
Another interesting Telehoist development is a three-partition coal tipper with a separate control for each partition. This body has been supplied to the National Coal Board and is used to facilitate separate deliveries of reduced amounts of coal withoitt handling. The partitions are locked by levers which project through slots in the floor, " leakage " of, coal being prevented by waist plates on the levers, which seal the slots when the body is in the normal running position. •
When tipping gear is fitted to a particularly flexible chassis, or one which is intended for arduous tipping. duties, the use of a stabilizer is recommended.