IN THE WORKSHOP.
Page 27
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Suggestions by Our Driver and Mechanic Readers.
HYDRAULIC tipping gear is need by a large number of commercialvehicle owners, and in some cases they have found, to their cost, the enormous power which the pump mechanism can exert. If the holding-down pins of the body be not removed before starting the Pump, serious damage can be done to the chassisframe. "E.J.," of Sandbach, suggests a " safety valve" of simple construction for which this Week's prize of 158, is awarded.
A standard half-inch T-piece pipe is Obtained, and into the single end is Screwed a pIug drilled §-in. internal diameter. The upperend of this plug is drilled and tapped with a I-in, gas thread. A second plug is then made with a §-in. hexagon head and screwed to suit the interior of the first plug. Between the two plugs is fitted a lead disc about the size. and thickness of a shilling. This is nipped between the shoulder in the first ping and the bottom of the second one.
This safety device can be fitted at any point in the pipe between the pump and the hydraulic ram. It is desirable to choose a spot which offers good facilities for inspection and replacement of the disc if necessary.
In the case of a vehicle with tipping gear working at 250 lb. per sq. in., the lead disc should be strong enough to withstand a pressure of about 400 lb.
per sq. in. In the event of the operator forgetting to release the body-holding mechanism, the lead washer merely bursts instead of causing the chassis to be strained by the power of the rain, and this may be the means of saving a considerable sum of money
AS in the case of all other mechanical
jobs, there are right and wrong ways of lining brake shoes. "D.McG.," of Benbecula, describes the method which he favours for doing this work. A common practice which he condemns is the riveting of fabric to the shoes and then running the vehicle with the brakes applied lightly to " run-in " the
new linings. Our contribute], suggests that the brake shots be removed and the lining detached, the old rivets being punched out and the shoes and drum then cleaned up in a paraffin bath. The next point is to find out the thickness of the fal.ric required ; the fabric should then be warmed, cut to shape and bent to fit the shoes without straining. Next chalk the inside of the fabric and place it on the shoe.
A jig is useful for the fitting work; this device consists of a piece of steel bar, which can be gripped in a vice, having a working end turned down to the same size as the rivet holes in the 'slew. The shoe is placed on top of the jig, which projects into the hole and acts as an anvil for holding the rivet head. On no account should -steel rivets be employed, aS they may cause serious scoring of the brake drums if they project above the lining at any time: aluminium or copper rivets are satisfactory. The heads of the rivets should be countersunk into the fabric and the edges of the lining trimmed up before mounting the shoes. When the shoes are in position, it should be noticed whether even contact is made. all round before finishing the job.
It is advisable to go over the pins and joints of the operating mechanism before being satisfied that the brake is in working order; all bolts and rods should be tightened and the compensating gear lubricated.
Petrol funnels naturally collect a large amount of dirt in the course of the season's work, and "D.IVIcer.'s " second hint deals with a method of removing the grit and solid matter from the filter gauze. .
A wineglassful of nitric acid is taken and mixed with an equal quantity of water. At the same time, a pound of washing soda should be dissolved in a pint of water. The materials are then ready for application, and the funnel should be fixed so that The liquids can be poured through without their falling on to the floor or on to any surface which matters—the skin included.
First pour the acid through the gauze until the dirt has dissolved, and then the soda solution should be used; this, of course, neutralizes the action of the acid. Finally, clean water should be used to rinse the gauze, followed by methylated spirit, which absorbs water adhering to the gauze meshes. The funnel must be dried before use.
TO reduce tyre wear, periodical checking of the wheel track is advisable. A set of trammels is required, and
" of Barnsley, suggests a useful device of this kind. A §-in, rod is taken,4 ft. 5. ins, long, or according to the types of vehicle to be dealt with. One end is threaded for 3 ins., the other for 1 in. The latter end Is Pointed, and two f-in. nuts are screwed on and locked together. At the other end—that is, the one having the longer thread—a butterfly nut is fitted. In the case of "E.C.L.," three types of vehieleIwere in use in the fleet, and be therefore constructed adjustable paints of three lengths to suit the various
wheel tracks. These points consist of Lin, steel bars pointed at One end and tapped at the other, to screw on to the long rod. By loosening the butterfly nut, screwing the suitable movable point up or down and locking with the wing-nut, any desired width, within limits, can be obtained.
The method of use is to mark the front wheels, both in front of and behind the axle, at equal distances from the floor; the trammels are then applied to the front of the front wheels and the pointer set to the correct meesurement, and locked with the butterfly nut. The trammels are then applied to the rear of the wheels, thus showing rtll variation of measurement between the track in front and that to the rear of the axle. The lodged nuts on the fixed end of the device are to afford a good grip, as greasy hands are the rule in the shop.