HINTS ON MAINTENANCE.
Page 64
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Notes on the Sentinel Valve Guides and Glands. Locking Differential Bolts. Attention Needed by Westinghouse Brakes. Peerless Overheating.
Sentinel Oil 'Glands and Valve Guides.
ON a Super Sentinel the oil glands often leak for the first 200 to 300 miles ; this is natural and will correct itself after a short running period. If the glands be tightened up it may spoil the packing ,and it will then be impossible to obtain an oil-tight joint until new packing is fitted. These glands are tested at the maker's works before being sent out and usually leak slightly When new.
It has in the past been necessary to lit a new valve chest, complete with valve-stem guides %hen the latter have become worn through constant reamering, thus permitting tob much play. This is no longer necessary, as new stem guides can be obtained and fitted at a cost which is trifling compared with that of a new valve chest.
Locking Differential Bolts and Nuts.
MANY cases of seized and smashed final-drive gears can be traced to theY looseninig of the nuts on file differential bolts or to the fracture of the bolt heads, the nuts or heads dropping into the axle casing and being caught up by the gear teeth.
To avoid any risk of such trouble occurring, one of
our readers has adopted the expedient of threading No. 16-gauge copper or mild-steel wire through holes drilled in the Volt heads and through the split-pin holes and castellatiens of the mite, Apart from providing a satisfactory locking device, this wire supports any broken head in position until the bolt can be replaced during overhaul. It is, of course, necessary to drill the bolt beads, but this extra work is even worth while, as it may save dismantling an entire axle and replacing such expensive parts as worm and wheel or bevel pinion 2nd chainwheel, as the case may be, and quite possibly a number of ball races.
Attending to the Westinghouse Brakes on an A.E.C.
WESTINGHOUSE brakes are excellent and powerful, but, like every other piece of mechanism, they require a certain amount of attention if their efficiency is to be maintained. The pressure for the operation is obtained from a reservoir, and under this is a drain cock which should be opened weekly to remove any moisture or oil which has collected. The small strainer inserted between the reservoir and the control valve on the steering column must be frequently cleaned by washing it in petrol, whilst the connections in the brake layout must be kept well lubricated to avoid losses through friction. The stiff working of the control valve is usually caused by want of lubricant in the rotary valve, which should be taken out, cleaned and smeared with lubricant.
et46 If a big reduction occurs in the reservoir pressure at each application of the brake, this is an indication that leakage is occurring in the piping. All the connections should be tested by painting the joints with soapsuds, applying the pressure along the pipe and noting any point at which bubbles escape. Any leaks should be promptly remedied. Check the lift of the ball in the pressure supply valve. The correct amount is .02 in. If the lift exceeds this, the pressure obtained will be too low. The supply pipe should be cleaned out every two or three months if the vehicle be in constant operation. To effect this, the pipes should be dismantled and a swab pushed through them, This will remove any oil or dirt.
The various filters should, of course, retain any solid matter consisting of large particles.
When taking up wear and resetting, adjustment should always be made to the rods leading to the brake drums. In course of time the shoe will need refacing. This is carried out in the usual way. To readjust after this operation, jack up both-the rear wheels, disconnect the brake rods and take up the brakes to the points where the wheels begin to drag. Connect up the brakes, apply several times to compress the friction material and afterwards readjust, if necessary. The pressure plates in an unloaded vehicle should not be more than in. from the diaphragm when the brakes are free. This will avoid noise and prevent vibration of the rods.
Overheating of Peerless Engines.
ENGINES at times develop overheating from some cause which one is apt to treat generally and consider unimportant. To remedy any inherent fault we must localize the trouble. The following summary will give the chief causes of this evil on the Peerless :— ,First, one must be quite sure that the engine is in a reasonably good condition and that there• are no broken piston rings, scored cylinders or burnt and leaky valvee.
To check for faulty water circulation, have enough water in the radiator to take a level just below the top water circulation pipe from the cylinder head. With the radiator cap removed and the engine running, one should be able to see inside the top tank of the radiator and observe a good flow of water from the said pipe.
Should there be no positive flow, proceed as follows: See that the interiors of the rubber hose connectione are not restricting the movement of water. Inside the front end of the water pump, where the elbow pipe from the bottom of the radiator is conneeted, will be found a sleeve with a wire gauze covering the lower end. To remove this for cleaning, take a flat piece of steel to fit into the two small slots and use an adjustable spanner for unscrewing. If trouble still occurs, it is often found that the helical gears of the water pump are assembled the wrong way round.The pump will be much more efficient if the gear teeth, which form a V shape, are assembled so that the base of the V is following the direction of rotation. The pins which pass through the water-pump driving sleeve may sometimes give trouble by shearing in the centre portion.
Another source of frequent trouble is the fan, due to the high speed at which this unit operates. To check the fan efficiency run the engine at a moderate speed and place a piece of paper or rag in front of the radiator ; this should remain tight up against the front if the fan be functioning properly. Next check the belt for the tension necessary to drive the fan, taking into consideration the high speed and diameter of this unit.