HINTS ON MAINTENANCE.
Page 30
Page 31
If you've noticed an error in this article please click here to report it so we can fix it.
How to Get the Best Out of a Vehicle, to Secure Reliability and to Avoid Trouble.
CONTRIBUTIONS are invited for this page from mechanics, works staff and draughtsmen, and fleet managers, drivers, garage foremen, and will be paid for on a generous scale. Every system, make, and type of commercial motor vehicle will be dealt with, and the matter should be written with a view to the disclosure of workshop and garage practice in the maintenance of a vehicle—practices which, whilst they may be quite normal, are peculiar to the particular vehicle and may not be generally known to those responsible for its running. Expedients and suggestions for overcoming roadside and other troubles are covered in the follQwing page, headed "Roadside and Garage." Communications should be addressed to "The Editor, The Commercial Motor, 7-15, Rosebery Avenue, London, E.G. 1."
140.—Curing Leakages in Firebox Screwed Stays
The screwed stays in the sides of the fireboxes of steam wagons and tractors are liable to leak after the vehicles have been in use far some 'considerable time. We do not propose to deal with the various causes of this leakage, but .would point out that if it is allowed to continue it will cause serious wasting, or corrosion, of the _plates. The usual method of stopping the leakage is to rerivet the heads by holding a heavy hammer against one head whilst riveting the other at the opposite end. In the majority of cases this proves quite effective, but there are times when a stay, after having been reriveted, will break out again, more especially if the threads of the screwed stay are not a good fit in the plates, or, probably, the holes of the firebox and shell-plate may be not .quite fair.
The best remedy for this, instead of drilling the stay out and replacing it by a new one, is to
expand it by the aid of a n steel pin. A 5-32 in. hole should be drilled down the centre of the stay, a little deeper than the thickness of the boiler plate, and the hole should then be opened out with a tapered reamer to in. diameter at the outer end. A tapered steel pin should now he made to fit the hole, and about f in. less in length than the hole. A little oil should be rubbed on the pin, which can be driven home with a hand hammer, thus expanding the stay.
It is a sound plan, if the pin is a good fit, to file a small groove down its length ; this allows any cornpressed air to escape.
141.— Front Wheels on 3 Type Thornycroft.
When the bearings of the front wheels 'of the J type Thornycroft vehicle wear to any great extent, a loud knock is caused when the vehicle passes over an uneven surface. To remedy this, obtain a fibre washer, or cut one out of a piece of fibre sheet, with a bore just largo enough to make a good fit on the axle. The thickness should be sufficient to allow a very slight amount of end-play. Place this packing ring between the phosphor-bronze bush and the thin steel adjusting washers.
B48
If both wheels are in bad condition, the other front wheel should be treated in a similar manner. Care should also be taken to see that grease is penetrating to the bushes, and give each Stauffer greaser at least a couple of turns daily.
142.—A Halley Correction.
In Hint No. 117, On page 486 of the issue of this journal dated November 15th last, there is a small error in the third paragraph from the end. The last sentence of this should read :—" For the cones mounted on stationary spindles there should be provided a free fit, the best being .0005. in., so that the cone will tend gradually to creep in service and thus distribute the wear." As it appeared, we gave .005 in., which is, of course, too great.
143.—The Check Valve on the Sentinel Steam Wagon.
, Engineers in charge of Sentinel steam wagons sometimes have a certain amount of trouble owing to the boiler feed pump refusing to function properly. If, after a careful examination of the pump valves (both suction and delivery) and the strainer, they appear to be in good order, the trouble is almost invariably to be found at the boiler check valve situated at the left-hand side of the boiler. When the pump is supposed to be operating, the delivery pipe is quite cool, right up to the boiler, but he valve in the valve box is stuck. This is not brought about by deposit, but by the valve splaying out in its seat and causing the guide wings to stick. The splayed edge can easily be removed by a small, half round file, and the trouble will then cease.
144.—Removing and Replacing Cylinder Heads • on Type P Halley.
The engine on the type P six-cylindered Halley chassis is provided with detachable cylinder heads, each held down by 16 nuts. In removing these heads, care should be taken not to•damage the joints, but to use the special lugs provided for hammering, in, order to ease the heads. Tn tightening them down after making the adjustments, care should be taken to strew down the nuts so that an even bearing is obtained over the whole head joint. To effect this, the nuts should he
screwed up in the order shown in the drawing repro. duced herewith, on which a number has been placed against each nut, giving the correct rotational .order in whichthey should be tightened..