ROAD AND WORKSHOP by Handyman
Page 51
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Steering Terms and Problems
TRACK AND TOE-IN are well-known words in the vehicle repair trade. But other words closely allied to the steering axle are not so well known and their true meaning and effect upon the steering assembly is less clearly understood. Let us take two other words of equal importance and examine their meaning.
First, camber. This is any inclination of the steering wheel past the vertical, and where the lean or tilt is outwards from the top, this is known as positive camber, just as any inwards lean is known as negative, or sometimes reverse camber. Camber is arranged during manufacture of the axle beam and stub axles, and on the heavy-goods vehicle it is usually positive camber of between 1.5 and 2°.
In the event of a bent stub axle, or axle beam, loose swivel pin or hub bearings, the required amount of camber can be lost or even reversed, and the following Visual or handling symptoms would be noted. Excessive positive camber would produce irregular wear on the outside shoulder of the tyre and would probably arise from a bent axle beam. The more likely event, however, would he negative camber caused by wear in bushes or bearings, and along with inner shoulder tyre wear, heavy steering would be noticed, with a definite tendency to wander about the road. If
taking up wear on hub and swivel assembly does not clear this fault, then either the stub or axle beam is bent.
Castor is our next term. This represents the amount of forwards or backwards tilt of the swivel pin at the top, and here backwards tilt is positive castor. Again, on most vehicles there is up to 2' of positive castor, and when all is correct. the vehicle can be driven "hands off" in a straight line on level ground. However, too much positive castor will again produce heavy steering, and quite often wheel wobble at speed. If less than the required amount of positive castor is in evidence, or even negative castor, several things will happen, including a definite " wander" and difficulty in keeping to a straight course. There will be very easy leftor right-hand steering, but no desire to' self-centre; in fact, this can be a very difficult task if negative castor applies.
If because of ditching or accident, the fault applies to one side only, it is certain that the axle beam is twisted, and the trouble will be at the side indicated by the steering pull ". On it being established that the beam is bent or twisted, it should be borne in mind that no do-it-yourself repair in the form of straightening should be attempted, as this is a specialized task in which heat treatment is involved.
Essex Prize-winner
THIS week's prize-winning idea comes from Mr. C. Martin, of Almesford, nr. Colchester, Essex, He states that on Bedford T.K. tractive units fitted with disc-type transmission brakes, the disc sometimes comes loose on the gearbox mainshaft. He suggests that to overcome this the standard bolt and locking tab can be replaced by a stud in the mainshaft and the disc secured by a Simmonds-type lock nut and shake-proof washer. This, he says, has been found to be very successful, with no failures reported to date.
Comments Handyman: I am familiar with the fault that Mr. Martin refers to and I think that the idea he has put forward is a good modification.