172.-1epairing Steam Wagon and Tractor Steering Chains.
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The steering chains of steam wagons and tractors are liable to get broken, either through the links wearing or due to an obstruction on the road, and sometimes through a faulty weld in a link, or it may be necessary to take a link out of a chain after the adjusting screws have been screwed home. A useful clip or shackle can be made from two pieces of 11 in. by in. mild steel, with a in. hole drilled at each end to take two / in. bolts, the bolt holes being placed far enough apart to allow in. between the adjacent links, the bolts being drilled to take in. split-pins, otherwise, in the event of the nuts slacking back and working off, a serious accident may be caused.
One of these shackles can easily be carried in the toolbox, and, in case of a link breaking, it will prove very useful. When it becomes necessary to take a link out, this can be done by tightening up the chain, • making a saw cut through the link and opening this out with a chisel ; the chain can then be coupled up with the shackle.
In some steering barrels the ends of the chain are fastened by studs, and in the event of these studs getting broken it may become necessary to drill them out. A good way is to take the barrel down and have each of the holes drilled right through, to take a bolt with a washer, as this is less liable to break, and is easier to replace if necessary. It frequently happens that one link in a chain weais more than the others' and in this case a few turns of copper wire lapped evenly round Ihe link where the wear is. taking place, will effectually prevent further wear. To avoid breakages the chains should occasionally be annealed at a red heat..
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173.—Maintaining Efficient Lubrication on the Lacre Engine.
The circulation of the lubricant is by pump, and the oil is contained in the crankcase sump, which normally holds about 14, gallons.
The oil circulating pump is bolted to the rear end of the sump on the exhaust side of the engine. Oil is drawn from the sump, and pumped under pres-; sure, via copper pipes, to the three main bearings of the crankshaft ; from these, via oilways drilled through the crankshaft webs, to the four big-end bearings. The latter each has a certain side clearance, through which the surplus oil passes. It is then thrown by centrifugal action on to the cylinder walls, small-end bearings, camshafts, etc., all of which it lubricates, and eventually drains down again to the sump.4 By this system, therefore, the 'oil is continually circulating, and is used practically over and over again. The daily addition of the small quantity of fresh oil which is necessary to maintain the prescribed oil level also serves to maintain the " body " of the oil. Nevertheless, after every 1,000 miles, the sump should he drained of oil, washed out, and refilled with new oil.
There are two filter gauzes, through which the oil passes. The one is in the crankcase filler and filters all oil put into the engine ; the other is fitted between the oil pump and crankcase sump. All the lubricant passes through this filter before reaching the pump. The danger of this ,filter becoming choked, and so stopping the oil circulation, is entirely dependent upon the cleanliness of the oil and of the vessels containing it, also the presence of the filler gauze when putting in new oil.
The pump filter should be thoroughly cleaned each time the oil in sump is changed: This filter consists of a circular tube of wire gauze, with a. blank end, inserted into engine sunup through a hole which the oil pump covers. On all hut the latest Lacre models it is necessary to remove the oil pump in order to , withdraw the filter. On the latest types this filter is withdrawn from the inlet side of the engine sump, without touching the oil pump, merely by removing twoin. nuts which hold a small aluminium plate oft the side of the sump. Then, by means of the
brass knob provided, the filter (together with the aluminium plate) can ha withdrawn from the sump.
174.—Air Locks in Water Circulation Systems.
Air locks in water. circulation are usually shown . by the fact that.the it in the -top of the cylinder jackets, the water return pipe, and the top section of the radiator, gets overheated to a considerable extent • and,if the defect is not spotted in time, boiling will naturally ensue. At the same time the water . the lower part of the radiator and of the cylinder jackets, the outflow pipe from cylinders, and water pump remains quite cold. Some air locks are caused . unaccountably, even on circulations where the system is above suspicion. Others are undoubtedly due to ' bad designI so much so that the designers, instead of attempting to rectify the defect, prefer to insert a small tap, which ahould be opened when filling up with water, or whoa an air lock is suspected. It is better, however, to remedy the defect.
It is as well always to stake sure that you have an air lock, for the same symptoms are also apparent when the water wheel inside the pump becomes detached from its driving spindle or when the key shears or the spindle breaks. To cure an air lock, it will probably be found most satisfactory to drain the water system entirely— radiator, _cylinder jackets, water pump, etc. .Then, provided the engine is not too hot, pour in cold
water with the engine running very gentl3r, and note againcarefully, when the system is again filled, whether there is a gentle and natural warming up of all parts concerned. A point I always -make before mounting the driving seat of a vehicle is to feel both top and bottom of the radiator, and note the relative temperatures. It is only the work of a second, and affords a fairly definite indication of the existing con
ditions. Should the water system he continually subject to .air locks, it must be carefully examined. Loops in pipes should be avoided, bends should be gradual, and allowance must be made for the fail and feed of the water ; by careful attention to all these points the trouble will he overcome.