RUNNING, UPKEEP AND OVERHAUL
Page 73
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Interesting Contributions from Maintenance Engineers, Drivers and Mechanics.
Refacing Mushroom Valves with Accuracy.
FINE of our correspondents, 'ILY" A.R.P.," of honey, points out that the ordinary universal self-centring chuck found on most lathes cannot be relied upon for holding any article true while turning operations are dope. When refacing a mushroom valve it is absolutely essential that the face be true with the upper part of the stem. It is, in most cases, impossible to turn the face with the valve between the lathe centres, as the saw cut will prevent a true centre being made in the valve at the head end.
Our correspondent has hit upon a very simple and effective form of steady which can be made easily, and will do for any size of valve. A V-shaped notch is Cut in a piece of i-in. by mild steel; this is shpported by means of an angle plate, or by any other convenient means, upon the bed of the lathe. The valve stem is then held in the jaws of the chuck, taking care that it only goes a little way into the jaws, and is then tapped so that it will run true. The V-piece can then be set so that it presses lightly on the stem as near to the head as possible, when the turning can be done without fear of the valve rising over the tool.
Should the stem have been bent, it Is possible with care to straighten it, but in practice this is usually mors costly than buying a new one. If the surface be too hard for the tool to make a start, it may be ground on an emery wheel to remove the hard skin.
Preventing the Fracture of Petrol Pipes.
THE subject of broken petrol pipes appears to be of everlasting interest to those who have to drive vehicles, especially machines which utilize solid tyres. We were of the opinion that all the tips that could possibly be thought of regarding the prevention of breakage of such pipes lied been suggested. A correspondent, " E.L.W.," of Victoria Park, London, E., appears to have found a tip that does not seem to have been mentioned before. • He tells us that by making a coil in the pipes, as shown in his sketch, near
to where the pipe joins the tank and the carburetter, that the risk of breakage is reduced to a minimum. Care must, however, be taken that there is 11 gradual fall all along the coil, or an air lock may be formed. He also says that when effecting an overhaul he sees that all pipes are carefully annealed by making them dull red-hot and cooling them in water. '
He also points outthat the breakage of pipes is oftendue to the poor way in whreh tanks are fixed to the chassis. A tank that can move under the influence of vibration is constantly putting a strain on any pipe that leads from it, so he takes care that the tanks are well sec ared.
The same correspondent suggests that the plan described by " F.II.B.R.," in our issue of March 12th, might be improved upon by substituting a felt washer for the rubber one suggested. The particular washer he suggests is a Ford washer No. 2,913, which can be bought from any Ford agent.
Handling Heavy Chains with Safety.
FROAI a correspondent, " A.W.," of Dewsbury, we have ,received the following two tips relating to the handling of heavy chains fitted to steam wagons. To carry such a' chain when taken off its sprockets is no easy matter, so " A.4V." lays it on the ground in a coil and passes a rod through the links ; then, with the help of his mate, he is able to carry it about with comparative ease and without the fear of his fingers getting trapped in it.
For replacing chains on their sprockets he suggests the following plan. The chain is mounted as shown in an accompanying sketch, with one end about level with the centre of the larger sprocket, then by -pulling the engine round by means of the flywheel one can get sufficient tension on the chain to get the lower run in place with the help of a mate. This can sometimes be done by giving the chain a smart jerk ; but if a board be-held under the chain to prevent it from sagging the coupling-up is made easier.
Aids to Easier Driving in Foggy Weather.
A DWELLER in the Fen district, of Wisbeeh, who has frequently to drive along roads where a river, or drain, runs along each side of
the road, tells of his experience in foggy weather and how he manages to prevent his vehicle from leaving the road through an error in steering, and pitching headlong down the steep bank.
His practice is to hug the grass on the off side of the road, as the light from the lamp oh that side shining on the grass or kerb is more easily seen from the cab. Sitting on that side he can see betterwhere he is than when driving on the proper side of the road. So long as the grass or other edging of the road continues he can keep to f-.3 mad, hilt when he comes to a turning he is temporarily lost unless there is a white line. The same thing occurs wherever the footpath is discontinued at
any place. : He wishes ,to impress upon his readers, and incidentally on the powers that be, that a white line at corners or where there is no well defined edge to the road would be of great value to those who have to drive at night in foggy weather.
It is true that to provide white lines along all roads would mean a great outlay, but in country such as the Fen district, where the slightest error in steering might mean Joss of life, we think his suggestion is well worth the consideration of local authorities dealing with road construction.