HINTS ON MAINTENANCE.
Page 68
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Lubricating A.D.C. Gudgeon-pin Bushes. Preventing End-play in a Thornycroft Camshaft. Attending to Boiler Gauge Glasses. A Leyland Dash Improvement. Play in the Foden Differential.
Reducing Wear on A.D.C.Small-ends.
AS the result of discovering that the gudgeon. pins and bushes on an A.D.C. engine were wearing somewhat too rapidly, it was decided to supply oil under pressure to these points instead of trusting to the oil vapour to provide effective lubrication.
For this purpose, four lengths of copper pipe were utilized, holes to suit these pieces of pipe being drilled in the housings of the gudgeon-pin bushes and the big-ends. Holes and oil-ways to correspond were also cut in the bushes and upper halves of the big-end bearings.
In fitting these pipes, the bearing caps and brasses were removed, the pipes pushed into position and firmly soldered into the housings, the brasses being then replaced. At the same time, the bottom ring of each piston was made Into a scraper type by bevelling off the lower edge of each groove and drilling a number of i-in, holes in each piston, these holes being situated just below the scraper rings.
A Safety Device for the Thornycroft Camshaft.
AN occasional trouble experienced with camshafts on eertkin Thornycroft engines is breaking of the steady screws which hold the off-side camshaft in position. This allows the camshaft to slip back from the oil pump, and, if not at once noted and rectified, may result in the big-ends and main bearings being damaged, as the lubrication will fail.
As a safeguard against this uncoupling, use can be made of a bracket contructed of a piece of 2-in. by 4-in. Rat mild steel, 12 ins, long, which should be bent to form a bridge for a 2-in, by fin. setscrew, the pointed end of which should be hardened and arranged to bear in the centre of the camshaft end, whilst a locknut should also be provided.
The bridge piece can be held in position by the studs on the housing at the rear end of the camshaft, ft-in. holes being drilled in the feet of the bridge piece for these studs, whilst the upper part of it should he drilled and tapped fOr the setscrew.
The Care of Boiler Gauge Glasses.
TFIE gauge glasses of steam wagons are of almost Wel importance. If allowed to become dirty or choked, with the result that a mistake is made in estimating the water level, serious trouble may ensue. Therefore the glasses should be cleaned regularly and the drains should be kept clear of deposit, particularly in some districts where the feed-water causes a deposition of lime inside the glass.
If any difficulty fie experienced in examining the water level, it will be found that a piece of white paper c46 held behind the glass will help considerably. In some cases use has been made of a small boat made of cork, painted red, but such devices are not always a certain indication, as they may stick.
Considerable trouble has sometimes been caused by the choking of glasses with the packing employed in making the joints between the glass and its mountings on the boiler. Perhaps originally correct, this may have moved under the influence of heat and pressure. This danger can be avoided by using as a packing a tapered rubber sleeve having a collar or flange at its thick end. This sleeve should be pushed over the glass tube with its thinner end near the end of the glass. A metal washer should be placed over the flange on the sleeve so that the rubber is gripped between the washer and the screw-down nut on the stuffing box. By this means the packing w11 be kept in its correct position
and there will be no danger of its working out
The Dash Brac4ets on the 4-ton Leyland. A TROUBLE sometimes experienced on the 4-ton Ley
, land is breakage of the dash brackets at the points where they are bolted to the frame. This allows the dash to rattle, also it is one of the chief causes of the breakage of oil pipes.
It is a good plar to fit brackets made of A-in. sheet steel to the outside of the dash and they can be held to this by 1-in. by 1,g-in„ bolts and nuts, being secured to the sides of the frame by the existing engine bolts, which are ft in. diameter. With the brackets in this position it can readily be seen when any of the bolts is getting slack. The exact form of bracket is a matter of individual taste.
Play in the Foden Differential Sprocket.
WHEN a Foden steam wagon has been in operation for a long time the back-axle chain sprocket sometimes becomes loose. This causes a snatch when the engine is started and the complete chassis is subjected to severe stresses.
The trouble is usually caused through wear on the bevel pinions, which are situated between the fast and loose bevel wheels. They endeavour to lift against the reaction of the teeth. To effect i! cure it is necessary to dismantle the driving side of the hack axle. There are three small bevel pinions rotating on spindles, and if these spindles be badly worn new ones are necessary.
There should be practically no up-and-down movement on the small pinions, and brass washers can be used to make up for any wear. To test the compensating mechanism lift the loose driving wheel off the ground and scotch the fast wheel, then revolve the driving wheel; if it be tight, one or more of the small bevel pinions are binding or are too deep in mesh, in .which case ease the packing washers with a file.