A MISCELLANY OF INTERESTING SUGGESTIONS.
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Useful Contributions From Our Driver and Mechanic Readers.
A Suggestion for a Transmission Brake.
THE suggestion of ",T.H.," of Belfast, for a foot brake on the transmission shaft is one that should prove of interest to the designers of new vehicles, rather than to users, but knowing that designers watch the suggestions of drivers and mechanics, -we put forward the suggestion as it came to us, and hope that its merits and demerits may be thrashed out. leIjo know that some have an objection to brakes on the transmission system and argue that should any part of that system fail the brake would become useless. In spite of this objection many vehicles are still made with brakes of the kind, so we think that the suggestion is worth investigating.
Our correspondent suggests the fitting of a cone-clutch type of brake, where the driver forces a conical drum on to a fibre-faced cone, as shown in his sketch. The arrangement is simple, but a severe' end-pressure would have to be borne by a thrust bearing at some point along the shaft. We would suggest that a. better application of the plan would be to use a plate clutch where the fibre is attached to the central plate and the rings which press on it equally from both sides would produce no end thrust. These rings would + be better able to radiate the heat generated if the fibre were attached to the central member. Our correspondent suggests that having an unbroken face the frictional surfaces should wear more evenly thoe when shoes press on a drum. It is well known that shoe facings usually we.aii Most unevenly.
On the Care of the Carburetter.
SOME useful information relating to
carburettere is given by " F.S.W.," of Broseley, Salop ; this suggestion regarding the broken petrol pipe difficulty is one of the simplest and most practical we have seen.
The following hints may be of use to drivers to enable them to obtain the best results from their carburetters : A very common and expensive fault is a leaky carburettor; this trouble is sometimes caused by wear on the bob weights which shut off the petrol when the float rises. These weights wear on the surfaces -which touch the float and thus allow the level to rise too high before they close the needle valve, causing a leak over the top of the jet.
To overcome this trouble the weights ran be taken out andput in upside down ; if after considerable use the trouble recurs, the weights can be taken out and some' strips of brass soldered on the worn surfaces until they are their original size ; this will give them a new lease of life.
The following simple test will show if the mixture be right :—With the vehicle stationary and the engine thoroughly warm, fully retard the spark and -then open the throttle suddenly; if the engine spits back into the carburetter the mixture is too lean, but if it takes the engine some little time to answer
the throttle and gain speed the mixture is too rich.
,If the carburetter has an adjustable air valve it is a simple matter to.adjust that to get the right mixture, otherwise it is necessary to fit either a larger or smaller jet, as the case may be, until the engine will respond properly.
With most lorries it will be found that the engine works better during hot weather with the hot-air intake pipe removed, but it would take the engine longer to warm up Properly without it. What appears to be the best idea is to drill two or more fairly large holes in the pipe close to the carburetter and fit a sleeve over the pipe with holes drilled in it to correspond.
There are several .ways of making a temporary repair to a broken petrol pipe to enable the vehicle to get home, but petrol pipes are not expensive and a couple of clips inside the driver's cab will keep a spare one out of the way. Some Hints on Driving a Steam Roller.
THE driving of a 15-ton Marshall
steam roller for some years has been the work of "All.," of Tamworth, and he gives us his experience regarding gears that run in oil baths. He says that ou a big road-making job the roller may be engaged on rough rubble for days at a time, where very slow speeds are used and where it has continually to alter its course, which brings the differential
into operation a good deal. He finds that through the gear being near to the firebox the oil becomes thin, especially in hot weather, and runs off the gearwheel before it reaches the top position.
To ensure a good distribution of oil he, whenever possible, finds a piece of good road, say, about 30 yards long, and drives his roller over this at a fairly high speed, with top gear in operation, taking care to start slowly and not to shake the engine about too much. He finds that owing to the higher speed the oil is thoroughly distributed over all the working parts.
He tells us that the lubricating cups feed the oil to the wicks better if a very smallhole be made in the cap to allow air to enter. The hole, he suggests, should be of about eirin. diameter. This, of course, only applies to those lubricators which are situated on parts where they do not revolve. The bole is best made in the side of the cap, as dirt is not then likely to find its way in.
A Simple Morris Tool.
FOR lifting the valves of -an 11.0 h.p.
Morris, " W.I.," of Chorley, has sent us the following: The tool is useful as a valve lifter and RS a tool for revolving the valve while grinding-in.
A piece of flat steel is cut out at one end to take a file handle or a brace, and has a hole drilled at tlre other end, which is then cut down with a saw to make the fork shown. The ends are turned up while hot, and a hole drilled at 1in. from the fork for a pillar or rest when the device is used for lifting valves. When employed for grinding, the fork prongs are arranged to engage the valve.
The rest of the pillar is made from a Fin. bolt with the head cut off and two nuts are used for adjustment for different sizes of engine.