RUNNING, UPKEEP AND OVERHAUL.
Page 33
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Interesting Contributions from Maintenance Engineers, Drivers and Mechanics.
The LObrication of Floating Bushes.
IT is strange that the principle on which the Michell marine thrust bearing works, namely, the introduction of a tapering film of oil between the faces of a bearing, instead of the scraping off of the lubricant by a sharp edge, appears to have had so little effect on the design of the bearings used in motor vehicles.
A correspondent, " W.S.," of Maidstone, has apparently recognised the importance of chamfering off the edges of the holes in the floating bushes used in the hubs of the road wheels of his vehicle.
He tells us that when first delivered to him these bushes have sharp edges to the holes which lead from the inside to the -outside for the purpose of distributing lubricant. The sharp edges, he finds, defeat the object of the holes, as instead of evenly distributing the lubricant they scrape it off the surfaces and retain it in the holes. To avoid this, whenever he has to fit new bushes he countersinks the holes on the outside, which is an easy job, but when he tried to treat the. inside in the same manner he was met with difficulty, which he overcame by making the tool he describes.
This consists of a piece of light carbon steel, which is bent and filed to Such a shape that it bevels the outside and the inside edges at the same time while it is being turned round by hand.
In the chamfering of such holes, also in the clearing away of the metal at the edges of big-ends and main bearings, it is essential to see that not only is there a distinct chamfer, but that it dies away gradually into the bearing surface, as the abrupt edge of a chamfer will act as a scraper.
When an Electric Lamp Fails.
FROM Bootle, a correspondent, "J.R.."
writes to say that with his lighting set the lamps are so wired that should one break its filament the other lamps in the same circuit fail also. As this is not an unZommon occurrence in his case, probably due to rough roads and solid tyres, he has adopted a plan by means of which he can be sure of not being without a light, should he not have a spare bulb with him at the time.
His plan is always to carry with him an old lamp that has broken its ffiament ; to this he solders a fine wire connecting the two contact points so that when in place it bridges the terminals. Although this lamp gives no light, it forms a convenient way of enabling the others in the circuit to be used.
It is strange that we have so many suggestions sent us for some way of dealing with a difficulty by means of some dodge, instead of by the proper means, namely, the carrying of a spare part.
A Slip in a Timing Chain.
FROM Birmingham, a correspondent, "EB.," tells us that in the fleet of 45 buses which he has to deal with, the majority of which is of A.P.C. make,
he is sometimes troubled by the chain which drives the camshaft slipping a tooth, which, of course, throws the timing of the valves out of its proper order.
He appears to have hit upon a simple way of correcting this trouble when it happens. His method is to un
screw one of the exhaust-valve caps and to watch No. 4 valve to see 'when it is just beginning to open, then to • place some article on the top of the valve so that the cap, when replaced, will prevent the valve from rising. He then slackens the adjustment of the chain and gently turns the engine until he hears the chain jump, after which he allows the valve to rise again by removing the cap so that the timing can be 'checked. A few trials will result in the timing being corrected, when the chain can be adjusted again and the valve cap replaced.
A Mirror Improvement.
MIRRORS, although a necessity
• now, are sometimes in the way of Passing vehicles when a lorry has to stop in a narrow thoroughfare. ' The driver of a steam wagon, " W.J.11.," of Hammersmith, tells us how he has made a folding arrangement which enables him to turn his mirror inwards when in a close place, as when standing in a tramway thoroughfare, or when entering the shed and packing up closely together with other vehicles.
To one of the uprights of his 'cab heattached a clip as shown, which can be made of flat steel bent around to form a bogs for a bolt. To this he attaches a lever to which the mirror is hinged. The faces of the lever and the clip can be serrated and a spring placed on the bolt to draw them together. • Stops can be made so that the position of the mirror when in operation can be easily located to give the correct image.
Trouble with a MorrisCommercial Gearbox.
wE hear from "E.H.," of Walsall, that he has had a one-ton MorrisCommercial brought to him -with some trouble in the gearbox. On examination he found that the nut which holds the ball bearing on the primary, shaft was coming loose and running away from the bearing. This he attributes to the driver trying to get into bottom gear while the lorry was running backwards.
He tells us that this is not an uncommon occurrence, as it happened twice to the lorry he had to deal with, and that he knows of other instances of this nut running loose through the same cause.
His method of curing the trouble was to screw the nut up as tightly as possible, drill a hole, as shown In his sketch, and drive a peg into the hole.
When this plan is adopted, care should be taken that the peg is either a very tight fit, or that the hole should be burred over.