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How to Keep Your Lorry Fit.—VI.

21st September 1916
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Page 9, 21st September 1916 — How to Keep Your Lorry Fit.—VI.
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The Sentinel Steam Wagon. The Well,known Production of Alley and MacLellan. Ltd., Po!Iliadic, Glasgow, and Sentinel Works, Shrewsbury, Forms the Subject of Our Sixth Article.

The Sentinel steam wagon, which we have chosen aa the subject of our sixth article on "How to Keep Your Lorry Fit," has several features entitling it to distinction_ It is fitted with a grate capable of satisfactorily consuming coke ' • the boiler is a water tube one, and the wagon is not fitted with any means for altering the speed ratio as between engine and rear axle ; in other words, a change-speed gear. is not provided. Last, but not least worthy of note' is the fact that it is so designed as to be capable of conveying six ions of net useful load evenly distributed over the body without infringing the regulations laid down by the Heavy Motorcar Order of 1901 with respect to axle weight.

Comparison Between Steam Wagon and Locomotive.

In the introductory part of this company's "Drivers' Handbook" —a manual which, by the way, should be in the hands of every Sentinel user—a comparison is drawn between the use and care of a railway engine and a steam road wagon like the Sentinel. It is pointed out with regard to the former that both driver and fireman come onduty half an hour before the engine is due to start, when they examine their charge, oil it, attend to the fire, etc. After the day's run, bath remain for a similar interval of time, which is devoted to another careful examination of the machineryL. The engine is then taken in charge by a cleaner and his assistant, who clean thoroughly every part, keep the boiler fire going, and prepare everything for the next day's, work; The engine has a shed day once a week, when the boiler is washed out and any repairs needed are done. Finally, a thorough examination of the boiler is made by an expert and a report on its condition is sent to the superintendent. If similar care were afforded every steam wagon, it would be a greater success even than it is. The essentials for obtaining good service are : the exercise of common sense, carefulness, and cleanliness. ,The driver does not need to be a skilled mechanic.

Oiling While Fire is Raising.

As pointed out on a previous occasion, a convenient time for daily attention to a steam wagon is in the early morning when steam is being raised, that is to say, each day before starting out. In particular, this time allows of complete oiling. Stress should here be laid on the need for taking care that all dirt and dust are carefully removed from the edges and lids of oilboxes, etc., before oil is poured in, otherwise harm is likely to result. The front axle journals are lubricated through grease cups on top of the pivots. These should be filled daily with a mixture of oil and grease, increasing the proportion of grease during hot weather. The rear axle boxes are lubricated through plugs ; these should be unscrewed and the lubricant replenished weekly. It is recommended that the cover be ,taken off each box every month and the pads cleaned with paraffin, afterwards rinsing them with tur pentine so as to remove the paraffin. Each morning the bottom drain cock of the engine case should be opened and all water which has settled in the bottom of the case at night allowed to drain away ; at the same time the oil level gauge should be examined, and if necessary fresh oil poured through the crankcase filler. The level of the oil in the, gauge should be kept always to 1 in. from the top of the glass. The same instructions in tote apply to the camshaft wheel case. During the cold weather, this oil level gauge occasionally becomes blacked with thick oil. In this event, the fitting should be taken oft, cleaned and replaced. The differential gearbox requires one pint of new oil through the plug at the side fortnightly. The joints of -the, reversing gear need oiling every day, and all grease nipples and cups should receive a turn daily. It is particularly important that the grease cup in the hub of the. right-hand rear road wheel be not neglected. Finally, the bath far the steering-gear screw should be filled fortnightly. In order to accomplish this, turn the lop of the steering wheel as far as it will go to the right, unscrew the plug in the steering column, and see that the hole in the bath in in Tine with that in the column, when oil may be poured in.

Shed-days.

The wore important adjustments and cleanings may receive attention on :shed days. These should occur at least once a week. In many cases, Saturday afternoon will be found tri be a .convenietb time. Attention to sundry points occasionally during the week, as opportunity occurs, will considerably relieve the pressure of work at the week-end. For example, it is possible, sometimes during the week, to blow down the boiler. This is .lone when the steam pressure is comparatively low, when the injector may be put on, the blow-off, cock opened, and a large proportion of the mud at the bottom of the boiler removed.

To Wash Out the Boiler.

On each shed day, the boiler should be washed out. Remove all the fire and Jet the steam pressure drop to about 10 lb., slacken off theplugs in the side of -the boiler at the bottom, and open the blow-off cock, finally removing the plugs entirely. Allow the boiler to cool gradually or the tubes may leak. When the empty boiler is becoming cold, reradve the top and fire-grate, and wash thoroughly inside the boiler with clean water, inserting the hose pipe in all plug holes, top and bottom. Thoroughly clean the outsides of the tubes and inside the firebox, removing all soot, dust and coke, especially from the corners where the tubes cross.

Hard-water Troubles.

It the water which you generally use is hard or impure, scale and deposit may be softened and removed from the boiler on shed day by putting a solution of washing soda, using 2 lb. to a pailful of water, into the full boiler, and keeping about 50 lb. steam pressure for about an hour. Then reduce the pressure, and empty and dean as instructions above. If the water is very hard indeed and causes hard deposit almost to fill the tubes, this can be prevented by putting,once a month, about a pound of washing soda dissolved in a pailful of water into the full tank, allowing this to be fed into the boiler. This operation must be performed cautiously, or the result will be priming of the boiler. '-For thoroughly cleaning the inside of the boiler, the firebox must be lowered and all scale and deposit removed from the inside of the tubes and walls of the boiler. If pure water is used, this need .

B40 only be done about once or twice a year ; if very bad, haad or dirty water is used, the firebox should be lowered and • the boiler thoroughly cleaned every second month.

To Remove the Firebox.

Complete instructions for removing the firebox are given in the Sentinel Co.'s ,handbook. A special caution never to take hold of the tubes or to hit or strain them in any way when lifting or lowering the firebox is important.

Test All the Fittings.

The fusible plug in the firebox should be removed, inspected, and cleaned at least once a month. Each week a wire should be passed through all passages in the watergauge fittings. The chock valve should be examined and any de-. posits cleaned out. The pressure-. gauge pipe should be removed at in

tervals and cleaned. The safety valve must be tested daily by allowMg it to blow at 230 lb. pressure. This valve needs occasional regrinding. The steam regulator glands should be packed with Palmetto packing when required. The piston-rod and pump-ram glands need examination weekly. When it is necessary to pack these, use pure asbestos half-inch square for the piston rods, and tallow hemp halfinch square for the pump ram. Clean the Crankcase.

Each month—that is to say, on every fourth shed day if these occur weekly—remove the crankcase back door to see that the chamber itself is clean. Drain off all water and oil, filtering the latter before using it again. Fill up with fresh oil to 1 in. from the top of the gauge glass. Treat the box for the cam-shaft in the same way. The feedpump valves should be examined weekly, cleaned and reground when necessary.

Driving Chains.

With regard to the main driving chain, the Sentinel Co. repeats in-, structions and recommendations which we have previously given both in this series and on other numerous occasions. It should be taken off at least once a month and cleaned, using paraffin, then put in a bath of hot oil. It is advantageous to keep a spare chain, cleaning and oiling one while the other is in use. The water tank should be washed out at intervals, according to the quality of water used. The water filter itself should be cleaned weekly.

Spring Clamps.

It is important that each week the front and rear axle bearing springs should have attention, the nuts on the spring clamp bolts must 'be kept tight ; they must, however, only be screwed up when the wagon is unloaded Care When On the Road.

The need for a proportion of the care of a steamer arises when the wagon is actually on the road. It is essential that the fire be kept clean and bright and spread evenly

over all the fire grate. The fuel should not be piled up high, a reasonable amount of space being left between fire and tubes for complete combustion. The ashpan door should be kept closed as much as possible when running. If steam pressure tends to rise, raise the water level, bearing in mind always that when going up-hill, the water level stands high in the glass ; it is

not a correct indication of the • amount of water in the boiler but exaggerates that quantity. During . the time the wagon is running, the boiler is fed by the feed pump, the amount being controlled by a valve. Reference to our illustration of the driver's cab will enable the reader to select the "pump return valve _handle." This should be screwed down for allowing more water to the boiler, and unscrewed to return water to the tank.

The Injector.

The injector is used to feed the boiler when the wagon is standing. If the pump fails to act or to prevent the safety valve -blowing off in towns, the following are possibly the causes: (1) It may be drawing air. Test the water cock and the suction pipe couplings, blanking off the injector suction pipe at the tank end and also the injector overflow. These should be air-tight. As a further test, unscrew the coupling nut, and place therein a coin or thin dise of metal of suitable size ; then open the water cock and the injector steam valve, looking for leakages at all points. (2) Steam pressure may be too high. Lower it to about 210 lb. (3) There may be dirt in the injector cones. Remove the plugs on each side of the injector, unscrew the cones, and carefully clean all passages. (4) The injector check valve may be sticking. Remove the plug covering the valve,

• and clean both the valve and its seat carefully.

Engine Timing.

If the engine thumps when run_ fling, the trouble may possibly be due to faulty valve setting. In order that the driver may test this, and, if needful, correct any errors, we reproduce the company's instructions for the procedure in full : First inspect and tighten all reversing gear joints to see there is no play here, or where levers are fixed to shafts. Remove,the cover A021 from the end of the gearbox on lefthand side of wagon, place reversing lever in " Start " notch, and measure how far the end of the camshaft stands within its bevel wheel. For wagons No. 236 and after it should be one-sixteenth of an inch ; if it is not, alter the length of reversing link, coupling wiper lever to control box lever, to suit.

To time engine valves, keep reversing lever in " Start" notch and remove driving chain. While your assistant turns engine crankshaft— by a spanner on chain pinion nut, tending to screw it on—try if all valves are properly seating. This is done by observing the clearance between valve stem and push rod at the moment when the opposite valve is being lifted. When a valve is properly seated there should be up to 1/32 inch clearance between the end of its stein and the push rod. If there is too much clearance the valve stem can be drawn out, and if there is no clearance the valve stem must be shortened slightly. Make quite sure the cam is not touching the push rod you think needs clearance before you shorten stem.

Having seen all valve stems have a little clearance, remove the inside valve cover at each end of that 1E-ft-hand side cylinder. While your assistant slowly turns crankshaft (still tending to screw on pinion nut) watch piston rod as it reaches the end of its stroke. When it has returned 1-32 in.. the steam valve (the inside valve that end) should open. To find out. the moment it opens, place your finger inside the valve and try to turn it ; while on its seat you can hardly do so, but immediately it opens the valve is very easily turned. If the valve is opening too early or too late it is easily put right by slackening the bolts fastening together the discs on the shaft running along lefthand side of engine and turning the disc nearest camshaft outwards or inwards to suit. All clearances being correct, if one valve is timed right all eight are correct. All four steam valves should, however, be tested to check time of opening of each. The four inside valves are steam valves, the four outside' valves are exhaust valves. Make sure that cam box is firmly fixed. Try bolts holding cam box plates to cylinders.

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Organisations: US Federal Reserve
Locations: Glasgow

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