WAYS AND MEANS.
Page 67
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Useful Contributions From Our ,Driver and Mechanic Readers.
The Advantages of Conical Bolt Heads.
BOLTS that are used to unite parts of motor vehicles subjected to great stress will often give trouble through continually working loose. A correspondent, " W.T.M.," of Grantham, tells us that he Hs found a way of fitting such bolts which has reduced the trouble to a minimum. He first of all reamers the hole and then countersinks it in both members, as shown in his sketch. Ile then procures a suitable bolt and nut and turns away the head of the bolt and the face °of the nut so that they fit the countersink, which, he suggests, should have an angle of 4:5 degrees to the axis.
This method, he points out, increases the bearing. surface and, consequently, makes a more secure job. He recommends that high-tensile-steel bolts should be used, and further suggests that bolts and nuts so treated might be kept in stock.
The plan is undoubtedly a good one so long as the countersinking is not carried too far, for in that case the members might be weakened. Where high-tensile bolts are not procurable, an old Ford back axle can be used from which to turn them, the steel from which these axles are made being of a very high grade.
Trouble When Re-assembling an Engine.
A TROUBLE which he had while re
assembling a Leyland engine is told to us by " A.W.," of Dewsbury, who thinks that the mistake he made might easily be made by others, so he gives his experiences as a warning. In the engine in question the valve-springs are held in place, not by the usual cotters, but by a pair of nuts. After he had fitted all his 'bearings with great Care, and had made sure that the crank would revolve freely in its bearings, he replaced all the valves, and to his surprise found that no effort on his part would induce the crank to turn, so after some consideration he removed all the valves and found that the crank revolved as freely as before.
From this he decided that there must be something wrong with the way he had assembled the valves, and after careful examination he found the cause of the trouble. It would seem that he had screwed the nuts so far up the valvestems that the springs were compressed to an extent which prevented the cams from raising the tappets 'to their proper height. By unscrewing the nuts so that there was less of the valve stem protruding from the lower nut the cam could then revolve in its normal manner.
The mistake he made was perhaps foolish one, but it is one of those things that might easily happen to others.
A Roadside Radiator Repair.
WE have an account of an accident,
and how the damage was repaired on the road, from "MI," of Leicester. Our correspondent, a mechanic, was sent to repair the damage done by an accident to a harrier lorry, the driver of which had run into the rear of another lorry standing in a place where there was no light. The driver rang up to say that the radiator was ruined, the water pump was knocked off, the fan and inlet pipe were also broken, and a few other less important parts were damaged. Our correspondent took with him a new radiator, a new fan, and a new water inlet pipe, but the pump left him guessing, as the bracket which holds
it was male solid with the top half of the crankcase. He fitted all the new parts, leaving the pump to the last. He tells us that he then had a brain wave, and fixed things up in the following manner.
He obtained a piece of 2-in, gas pipe bent at right angles, a short piece of 2-in, water hose and a piece of 24-in. hose. The 2-in, hose he fitted on to the bottom of the radiator inlet pipe. He then slipped another piece of the same hose on to the L bend, and the 24-in. over that and on to the inlet pipe across the front of the engine—A J.H4 type Tylor. He then secured all joints with hose-pipe clips and tells us that this made a sound job of it. So good was the job that the engine was left running
like this uatil some time later when it could come into the shops for further work. No boiling or other trouble occurred, despite the cutting out of the pump.
High-pressure Greasing.
IIIGH-PRESSURE greasing, which has displaced the ordinary greasecup system of lubricating the parts of vehicles, although, broadly speaking, a simple and effective system, requires a good deal of attention to several points in its working. " D.MacG.," of Benbecula, points out that one may give too much grease at one 'point whilst some other point is starved.
To get the best results one's maxim should be "Little and often."
Taking, for example, the nipples conveying grease to the back wheel and axle bearings. The grease flows into the spaces around the bearings, and 'when one screws the gun down no resistance is felt, with the result that one is liable to go on screwing and so overgrease the bearings, causing waste and in many cases forcing the grease on to the brake drums, making them lose their effectiveness. On the other hand, when the gun is applied to the shacklepins, in screwing these down, one should make sure that grease exudes from both ends of the bearings, or one side may be well greased whilst the other side is as dry as a bone.
A New Form of Silencer.
A CORRESPONDENT, " H.J.0.," of Ashingdon, Essex, sends us a sketch and description of a sileneer he has recently made. He tells us that it has given great satisfaction and is cheap to produce. An aluminium casting forms the outer shell and both sides can be east from the same pattern. The ends are bored to fit the inlet and outlet pipes, to which they are held by
split clamps and bolts. Between the faces of these castings is placed a plate Of metal which is provided with a' number of holes, the sum total of the area of which is more than that of the inlet pipe. By this means undue back
pressure is avoided. A valve can be fitted to allow of a clear way through and can be operated by any convenient means, such as a Bowden wire. The designer points out that this silencer is very easily cleaned, as all one has to do is to take out the bolts which hold it together an slip out the central plate. This can then be cleaned and replaced with Rase.