ANSWERS TO QUERIES.
Page 20
If you've noticed an error in this article please click here to report it so we can fix it.
Our readers will be informed by the Editor on any points connected with the construction or use of commercial motors. Where a direct reply is desired, a stamped addressed envelope should be enclosed : if a request for privacy is not specially made, any query and answer may be publiShed.
Starting-up on Coal-gas.
[4383] (Taunton).—Provided you have proof that the mixture of gas and air is correct, you should have no real difficulty in starting up. We should think that the cause of the difficulty is that the sparking-plug points are too far apart; for coal-gas they require to be set considerably closer than when petrol is used. Air should not be shut right off, because you have. got the fuel in a gaseous form, and gas alone will not give you an explosion. The need for shutting off extra air with petrol is in order to get the petrol on the move and -to convert it from the fluid to the gaseous form, sufficient air passing through the Choke tube for the purpose.
Mileage and Petrol Consumption.
{4384] (Liphook).—It is very difficult, without knowing the actual country over which you are running your vehicle and without knowing what the vehicle is, to -say what you should get in the way of mileage from your petrol, but you may take it that as a general rule one gallon of petrol when used for road transport should produce 50 ton-miles of work. • Assuming the weight of the vehicle to be one-half of the gross weight, it should be possible for you to get 25 ton-miles out of a, gallon, that is to say, that you can move one ton 25 miles or 25 tons one mile, so that on a three-mile Journey you ought to be able to move 8-1 tons ; on the return Journey, if the vehicle is empty, you ought to travel on equally level ground just twice the distance on a gallon ; if it is downhill you ought to get better mileage even than that.
Tractor Couplings.
[4385] (Cradley Heath).--The two safety couplings which we know to be practical are the Fowler Safety Hitch and the Browne Patent Safety Drill Bar. We have sent you a rough sketch of each, which will give you, some idea of their method of application.
The Fowler Safety Hitch is tied by a strand of soft iron wire, 18 or 20 gauge, the least possible number of turns ,consistent with the• work in hand being wound to hold the safety link in a closed position. The number of turns of 18 gauge wire should not exceed five, or of 20 gauge wire should not exceed nine.
The Browne Patent Safety Drill Bar depends, we might point out, on the closing spring, and only when such a tension comes on the drawbar as will compress the spring far enough to release the catch does'the latter become unhooked. The address of the inventor is Patrick Browne, Caibre, Abbeyside, Dungarvon, Co. Waterfond.
Gas and Petrol Figures for a 50-cwt. Vehicle:
14386] (Nurseries).—With a gas-holder having a cubic capacity of 500 ft., which is the size you should be able to carryon your 2-ton vehicle, you could run from 18 to 20 miles per charge, according to the condition of your engine. If your regular journeys are 16 miles out, and back, you should therefore be able to fill the holder before starting out, do the outward journey, have-the bag refilled, preferably while discharging the load, or while loading up the empty cases, and then return. This is, obviously, a most convenient and economical method of working. Regarding your 21-ton vehicle, this, working under the foregoing conditions as reganfls length of journeys, would require a gallon of petrol for 10 or 12 miles of running, according to the condition of the chassis and also in inverse proportion to the skill of the driver. A new 2i-ton lorry should be obtainable for 2700. You would have to pay about 2500 to 2550 for a really good second-hand one. ' Fitted complete the gas outfit would cost from 225 to 230.
Approximately, the cost of running a 21-ton vehicle at the present time, reckoning on a regular mileage of 400 miles per week, is 11d, per mile. As the mileage decreases the cost per mile rises slightly, owing to the effect of the standing or overhead charges.
Wants a Secondhand Two-tonner.
[4387] (Jersey).—For a really reliable second-hand 2-ten vehicle, you will have to pay from £300 to 2400, according to the condition of the chassis. The price • is undoubtedly high, but the demand is greater than the supply. You can buy vehicles of this .capa,eity for less, but you would probably not be satisfied with the results. Reliable dealers in second-hand vehicles in the London district are : Arid l Motors and General Repairs, Ltd., 320-2, Camberwell New Road, London, S.E. 5; W. Rinman, 1 to 5, Fitzalan Street, Kennington Road, S.W. 1; The Brixton Carriage Works, 53, Acre Lane, Brixton, S.W. 2. You should also communicate with advertisers in TEE COMMERCIAL MOTOR.
French Inquiry for Tractors.
[4388] (Landes, France).--One of the best self-contained machines on the market is the Moline, which you can obtain from British Empire Motors, Ltd., 115, Fulham Road, London, S.W. The Wyles is also a good self-contained machine, and is made by John Fowler and Co. (Leeds), Ltd., Leeds, and Wyles Motor Ploughs' Ltd., 5, Carr Street, Manchester. Another British self-contained plough is the Crawley, made by the Crawley Agrimotor Co., Ltd., Tower Works, Saffron Walden.
We think that you want to ensure buying a machine that can be used for general purposes. The only time that farmers are willing to pay good prices for ploughing is immediately after the harvest ; at other times ploughing is done at cut rates, and you want to be able to keep the machine employed on other work practically throughout the rest of the year.
Piston Ring Technics.
,[4389] (Birmingham)—The outside diameter of piston ring blanks is 1.025 times the bore of the cylinder: This covers an allowance of eight thousandths of an inch per inch in diameter for grinding after the rings 'Etre out. The width of the slot is 0.09 times the bon of the cylinder, and the clearance between the ends of the ring when hi place in the cylinder, to allow for expansion due to heat, is equal to the bore of the cylinder in inches divided by 250. On this basis a 90 mm. ring would be 93.15 ram. outside diameter when turned. The slot in the ring, when free, would be 8.1 mm. wide, and the width of the slot when the ring is in place, allowing for expansion, is 0.36 mm. The outside diameter of a, 4 in, ring as turned would be 4.658 in., the width of the slot is 0.4 in., and the clearance between the ends of the ring .when in place in the cylinder 0.018 in. The amount to be ground off-the 90 mm. ring when cut would be 0.72 mm., and the corresponding allowance on the 4i in. ring would be 0.030 in.