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Power-assisted Steering

21st November 1952
Page 58
Page 58, 21st November 1952 — Power-assisted Steering
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Which of the following most accurately describes the problem?

A POWERED steering mechanism ti forms the subject of patent No. 679,346, which comes from Ross Gear and Tool Company, Lafayette, Indiana, U.S.A. A feature of the scheme is that power is not applied until the steering effort increases to a pre-determined value.

The steering column (1) drives a worm (2) which, when revolved, turns the rock-shaft (3) by means of a forked Lever (4) which acts as a nut on the worm thread. The lever is extended to embrace a block on the piston-rod of a hydraulic cylindet (5)... The ballthrust races (6) of the worm are backed by spring washers, so that heavy steering effort will compress one of them and shift the worm endwise.

When this occurs, a hydraulic controlvalve (7) comes into action, and directs fluid under pressure to one side or the other of the servo-piston, thus amplifying the effort. If the steering force be only light, the movement of the spring washers is unsufficient to work the control valve, and then the whole effort is provided by the driver.

This means that the power system is not constantly at work for minor deviations, which must save much unneces sary wear. The patent also shows some detail modifications, the principle, however, being the same.

HYDRAULIC PUMPS FOR TIPPERS

DATENT No. 679,136, comes from 1 Edwards Brothers (Tippers), Ltd., and others, Bradford Street, Bolton, Lanes,, and deals with improved control of the ram of a hydraulic tippinebody.

The drawing shows the pump used, complete with safety valve and manually operated pressure release.

The pump is driven by shaft 1 which 'oscillates the plungers (2) via a swashplate (3). The various plungers deliver their outputs to a common take-off port (4) which leads to the ram cylinder. A40 Connected also to the output side is a chamber containing a spring-loaded ball (5) which, if opened. shortcircuits the pump via port 6. Although normally closed, the hallvalve will open if the pressure rises beyond• the pre-set value.

The same ball can be manually opened to lower the ram by allowing the trapped liquid to escape from the pressure side; a handle-operated push-rod. (7) performs this function. It is a feature Of the patent that the handle should be placed within reach of the driver when he is in his cab.

BATTERY TEMPERATURE

VVEHICLE batteries will work satisfactorily over a normal temperature range, but excessive heat or cold will reduce their efficiency. To avoid these extremes, patent No. 678,343, shows a scheme for warming or cooling the battery by including it in the air-conditioning system provided for the interior of the vehicle. The patentee is Daimler-Benz A.G., Germany.

A FORE-AND-AFT TIPPER PATENT No. 679,362, deals I with tipping arrangements for

refuse collection bodies, and refers particularly tb vehicles intended to operate in narrow streets and passageways, or in other circumstances where side loading is impossible. The patentees are C. Edwards and Shelvoke and Drewry, Ltd., Letchworth, Herts.

The body described is emptied by rearward tipping, the power being supplied by a single hydraulic ram lifting at the centre of the body. Such is fairly conventional practice, but the novelty in this case lies in the fact that by changing over the locking bolts, the body can be tipped in a forward direction as shown in the drawing. This is the method used for shifting the load to the front when more space is needed at the rear of the body. The advantage of the scheme lies in its simplicity, the only additional part being required is an extra set of locking bolts at the front.

Whilst the scheme is of greatest utility when applied to small refuse-collecting vehicles, it is capable of application to all types of load-carrying machine.

SUCTION CONTROL OF INJECTION PUMPS

To operate the control rod of an injection pump in accordance with the air charge, is the aim of a scheme shown in patent No. 678,213, by Robert Bosch G.m.b.H., Stuttgart, Germany. The method disclosed has the feature of giving art extra-rich mixture at idling speeds, which suggests it may be intended for engines using petrol injection.

The injection pump is controlled by a flexible diaphragm (I) which is piped to a bore (2) located on the downstream side of the throttle-valve (3). This gives what may be called normal control, injecting more fuel as the suction decreases. In parallel with this bore is a second one (4) which emerges on the upstream side of the throttle. . At full throttle this has little 'effect, but with a closed or nearly closed throttle it 'passes a little air and so causes the idling mixture to be enriched. Both orifices are fitted with adjusting screws to give accurate cali

bration. The patent gives a graph showing the operation of the device at all engine speeds.

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Locations: Lafayette, Stuttgart

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