152. — Oil Release Valve on Dennis Engines.
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The oil release valve utilized in the lubricating systems of all the engines of Dennis commerical vehicles made since 1914, with the exception of the 30 cwt. and one ton chassis, is situated at the rear end of the exhaust camshaft and can be removed quite easily by releasing the large brass cap nut. The function of the valve is to release the oil pres sure and permit the lubricant to enter the exhaust camshaft, which is hollow. The valve should be removed every two or three thousand miles and thoroughly cleaned.
153.—Points Requiring Attention in the Care of Steam Wagons.
White so much stress is always laid on certain of the drivers' and garage hands' duties, that are in no danger of being overlooked—such as washing out, gland packing, and valve testing—there are several details which are far too frequently neglected. True, they are generally those of lesser importance, but they are still far too important to be neglected with impunity. A good many of them are jobs that occur only at comparatively long intervals; the performance of the duties that require attention daily or weekly get automatically ensured by the routine. It is the jobs that come up only once a month, or still less frequently,. that are forgotten, and I think, therefore, it would be best to draw up a monthly programme. Such a programme would include !— . 1.—Removal of the fusible plug and cleaning out of all scale. 2.—The clearing out of water passages between the boiler and the pump, and between the boiler and the injector. Scale is likely to he the chief obstruction here, and if the pipes are curved the simplest way is to soften the deposit by taking the pipes off and boiling them in as strong a solution of ordinary washing soda as the water will carry, leaving them to soak in it for as long as possible, preferably twenty-four hours. If the passages arc straight, they A34 can be cleared by a bit of fiat steel twisted like an auger bit, and hardened and ground on its edges. 3.—The feed-water heater should be taken down and cleaned. If it is exhaust heated, as most are, oil from the steana supply to the valves and cylinders may get deposited here and require removal. 4.—The reservoir for the mechanical lubricator for steam chest and cylinders should be emptied and swilled out at least once a month if the wagon is doing any reasonable mileage and the opportunity may be taken to -see that valves and passages are also clean and clear. 5.—The casing of the balance or differential gear should be emptied of oil, washed out with paraffin and refilled with clean, fresh oil. 6.—On most steam wagon axles the bearing surfaces are applied only on the upper sides of the shaft. The underneath part forms a sort of oil well in -which woollen pads are held up against the journal by spring pressure, and thus continually wipe and lubricate the journal as it rotates. In others the same office is performed by cotton waste, with which, by the way, horsehair may be mixed with advantage to give it springiness. In any case, every month these wells should be emptied, thoroughly cleaned out with paraffin, and then replenished with fresh oil and fresh waste, or, if necessary, with fresh pads. Then, every two months or so the driving chain should he removed, and, after a thorough cleaning in paraffin, should be submerged in a tray full of a mixture of tallow and graphite warmed to the liquid stage, and well stirred. To allow the lubricant to reach all parts, the chain should be left for some time in this bath ; in fact, preferably the whole time the boiler is being washed out. It is well to have an alternative chain that can be brought into use when the other is under treatment. In replacing, the adjustment should leave the chain not too tight. There should be a Certain amount of sag, which will vary according to the length of chain, but, broadly speaking, one may put the sag at fi ins. for the shortest, and about 3 ins, for the longest, chains. The seri teng chains, too, should have attention every couple of months at least, and should be taken up so that the spring in each-chain is just slightly :tinder tension.
154.—Care of Water Pump on Autocar Engine.
The water circulating pump is of the centrifugal type and is driven directly from the engine. It is „equipped with two packing glands on the shaft, which ehould be tightened from time to time whenever there is any indication of leakage. Care should be taken, however, never to use any great pressure on the packing nuts, for so soon as the packing is .squeezed up to a solid condition, its usefulness is ended, and it should be replaced. In tightening up the nuts, note that the front one has a right-hand thread and the rear one a left-hand thread. It is advisable to flush the entire water system about once a month to remove any rust, dirt, etc., which may have settled in the pip-en., and radiator. To do this-, let the engine idle ; put a hose in the radiator filler, open all petcocks and allow just enough water to go through the hose to keep the radiator filled.
After running for a few minutes, the water will be clear. Then close all petcocks and remove the hose. The two grease cups should be turned down weekly. In order to prevent the water from leaking through the packing, a special grease must be used for these cups. Do not use ordinary grease. A grease that will stand contarctlwith hot water is necessary.
The oil gun must be used on the two special connections for the lubrication of the ball bearings in the pump.