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For DRIVERS, MECHANICS, & FOREMEN.

8th February 1921
Page 29
Page 29, 8th February 1921 — For DRIVERS, MECHANICS, & FOREMEN.
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Which of the following most accurately describes the problem?

TEN SHILLINGS is _paid to the sender of any letter which we publish on this page, and an EXTRA FIVE SHILLINGS to the sender of the one which we select as being the best each week. All notes are edited $efore being published. Mention your employer's name, in confidence, as evidence of good faith. Address, D., X. and F:, "The Commercial Motor," 7-15, Bosebery Avenue, London, EX; 1, Lamps Alight.,

On Saturday, February 12th, light your lamps at 5.37 in London, 5.39 in Edinburgh, 5.34 in Newcastle, 5.46 in Liverpool, 5.43 in. Birmingham, 5.47 in Bristol, and 6.29 in Qublin.

More Help for "Worried Driver."

We publish herewith the remainder of the letters received offering suggestions and advice to "Worried Driver," whose letter, dealing with an oiling difficulty on a Iwo-cylinder Thornycroft engine, appeared in. our issue for December 21st. We are paying 7s. 6d. for each of these letters, but frora next week, we shall revert to our usual awards as enumerated at the top of this page.

(2,188] " Interested " (Gateshead) writes:" Worried Driver' should remove the plugs in the ends of the oil holes and thoroughly sluice the passages out with paraffin. If he does this before be fits the next big-end brass, he will find his trouble is at an end. It is impossible properly to clean a crankshaft out without removing these plugs."

[2,189] " A.E.K.114" (Plymouth) writes:—" I su_Kgest that 'Worried Driver's' trouble is due to the oil hole in the main bearing not registering with that in the crankshaft. Some time ago I had a, similar trouble with an A.E.C. lorry (Tyjor engine), which I eventually overcame by elongating the hole in the bearing till it did register. I found, too, that the oil pressure was insufficient, and increased it to about 30 lb. per square inch by stretching the spring of the release valve. Before making these alterations I ran four No. 4 big-ends out in 250 miles. Since the alteration I have travelled 8,090 miles without a single .involuntary stop."

[2,190] " J.J.E." (Basingstoke) writes:—" Worried Driver's' difficulty is probably due to the connecting rod being out of line. If this is so, you will find that the piston is bright, top and bottom, on opposite sides. Line the connecting rod up so that, while the bearing is in the centre of the crank-pin journal, the rod itself is square with the crankcase and central with the bore of the cylinder. When starting the engine up, note the behaviour of the oil pressure gauge. It should register at least 5 lb. If it does not, remove an inspection cover, and, while the engine is running, look inside the crankcase, lighting it up with an electric torch, and see which bearing is losing the oil. Do not take the lorry out unless you are certain that the oil channels are thoroughly clean, and the oil pressure is registering from 5 to 15 lb."

(2,1911 " D.A.C." (London, N.W.6) writes :—" Worried Driver's' trouble is due to one of two things, either to incorrectly drilled or cut oil ways or grooves, or to an inefficient pinup. Since the trouble commenced after new main bearings, had been fitted, it would appear to be quite possible that the oil hole which should have been drilled in the main bearing has been forgotten. Alternately, it has been drilled in the wrong place.

"The oil grooves which are cut on the inside of a main bearing such as this, are frequently formed in the wrong direction. This is most likely to occur if the mechanics employed on the job have not been used to engines in which the oil is forced to the confleeting rods as well as to the main bearings, lthough it really applies wherever the oil is .delivered to the maia bearing from the inside of the crankshaft. When forced lubrication is employed, the grooves in the main bearing should be cut across, and not along, the brass, or at least this applies to the groove which comes opposite the oil hale in the crankshaft. If this groove is cut round the bearing, so as to occupy nearly the full distance between the faces of the 'joint, then the oil will be afforded ample opportunity to emerge from the hole in the crankshaft, since it will be open to this groove for nearly half a revolution of the engine. If, on the other hand, the oil groove is out :long the bearing, the oil only. has a chance • to escapeoccasionally, just for the instant when that groove is opposite the hole. "If there is wear on the teeth of the oil pump or wear in its bearings, the oil supply will be considerably reduced, and it may even be necessary to fit a new pump."

A Simple and Easily Made Bonnet Rest.

[2,192] " G.B," (Waltharastow) writes —".1 have noticed during the course of many years' experience with motor vehicles that many of the bonnets covering the engines assume a bad fitting appearance, owing to being constantly thrown right over when opened for inspecting the engine or for other reasons. Opening bonnets in this manner sometimes causes a serious straining of the hinges and rivets with the result that after a short time the bonnets will not bed down on the plinths, and, even. when fastened by spring catches, they rattle owing to vibration and thus cause considerable annoyance. "The accompanying -sketch shows a very simple device which can be fitted to one of the bonnet slides at each side of most motorvehicles. This device consists of a spring about 6 ins. long riveted to the inside of the bonnet slide and carrying at its upper end a small brass clip, which can be modified in shape to suit the bottom of any type of bonnet. A holens cut in the bonnet slide in order to allow this clip to project directly the bonnet is lifted clear. It is then only necessary to lower the bonnet down the slide until it comes to rest in the slot.

"In the particular example I made, the spring employed was an old hack saw blade, suitably tempered to prevent breakage."


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