Lacre Hauling Gear and Power-plant.
Page 29
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On the Latest Six-tonner,
Following our scheme for supplying our readers with detailed particulars of now chassis well before the Olympia Show, we recently paid a visit to the Lacre Motor Car Co., Ltd., at Letchworth. The outstanding feature of our visit was the inspection of a six-ton chassis, fitted with a new hoisting gear.
Our illustrations show that the general design of this machine is clean and workmanlike. A four-cylinder engine with the cylinders cast in pairs, aim with a bore and stroke of 41, ins. and 6 ins, respectively, is employed. This engine is rated at 40 h.p. nominal, but on the brake test 50 h.p. has been developed. A governor automatically acting on the throttle cuts down the engine at 1150 r.o.tn. The lubrication is by pump, driven from the camshaft, and particular attention has been paid in order to ensure that the oil reaches every working part of the engine. The drive is taken through a leather-faced voile-clutch of ample size by shaft to the gearbox. which gives four speeds and a reverse. The gearbox and differential form one complete unit. The final drive is by means of duplex side chains.
The spring shock-absorber fitted on the main drive between the clutch and gearbox, of which we give an illustration, is of value under heavy-service conditions. The object of this spring drive is to allow of some little elasticity between the gears and the clutch when the latter is engaged. The frame is in. swepta little towards the front, and is stiffened by strong gussets. The forward end of the propeller shaft is supported on a separate bracket, so taking the weight from the clutch. Usual-typo worm and segment steering is fitted.
Driven by dogs from the tail-end of the gearbox, the drum-shaft, which is of ample diameter-3 ins.—is carried through to the extreme rear of the chassis, and it runs in bearings of ample size. The control for the hoist-drive demands some little attention, by reason of its ingenious simplicity. At t'he gearbox end, the fingers of the clutch are of double the usual length. When it is desired to transmit the drive to the road wheels, this clutch is entirely disengaged. When in position for the drive to the hoist, however, the dog-clutch is partly engaged. When engaged to its
limit, the spur-pinion for the hoist-drive is brought forward by the sliding of the shaft, clear of the pinion, and a second dog-clutch at the extreme rear end of the hoist-drive is so brought into engagement ; this drives a 41-ins. by 14-ins. crowned pulley direct. Provision has been made when designing the chassis for the fitting of a pulley up to 3 ft. 6 ins. diameter. The third position is for belt drive to threshing engines, machine-tools, dynamo, etc. The shaft to the hoistinggear is controlled by a lever located on the side of the chassis frame. This lever works in a notched quadrant. A spring adjustment is provided which enables the gear to be worked by one man in case the dog-clutches cataot oe ingaged owing to the position of the iiana elatch, the engine rail be started up, sad on tiie turn, when the dog-elm-Ales are in a position for engfigtinent, the spring drives the gears home. Actual teste have shown the hoisting-gear to be capable of lifting a fully-loaded six-tonner up a 1 in 3 gradient, a direct pull on the cable of 8000 lb. being possible. A feature which
calls for attention is a second spring. controlled dog-clutch fitted to the axle, by means of which one sprocket fan be disengaged, and is left idle.