A PB1ZE OF .TEN SHILLINGS is .awarded each week to
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the sander of the best letter 'which we publish .0k. this page> all .others paid for at the rate of a penny a tine, with an allowance for photographs. All notes are edited before being publiAed. Mention 7oar employer's same. in confidence, as evidence of good tali& Address D., M. and F., "The Commercial Motor." 7-15, Bosebery Avenue. London, EX, Lamps Alight. • Light your lamps 'at 9:30 in London, 10.57 in Edinburgh, fi.55 in Newcastle, '9.51 in. Liverpool, 9.42 in Birmingham, 9.39 in Bristol, and'10.3'aiq Dublin.
An Engraving Tip.
. [17441 " GB." (Hornsey) Writes There aro
many useful hints and tips, .formulT, -recipes, and so on handed on from one generation to another of workmen, which might usefully be published from time to time in the space afforded by yonr D.M. and F.' page. Particularly does this remark apply -at the moment when, owing to shortage of labour due to recruiting,_ not to mention the effects of various substitution' schemes, a great deal Of the personnel of the industry is new. The following method of engraving on steel, fairly well known as it is, may on this account be well worthy of publication.
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"As a rule, any artitile likely to need engraving is small enough to be warmed over -a gas ring or brazing. hearth. It should be so heated until it is at a temperature that will allow of its being -touched bY the cheek ; no hotter than this, nor Cooler. A little beeswax should now be smeared over the part which it is desired to engrave, and, in preparation, a piece of blue stone should be dissolved in twice_ its volume of water, a pinch of salt being added to the solution.
"When the beeswax is set, the design to be engraved .should be 'cut through the wax with a scriber._ The sharper this tool is, and the more frequently it is cleaned during the process of engraving, the better will be the result. The alext operation is to cover the marking with the blue-stone solution, and leave for a couple of hours. If the wax and the solution be then removed, the marking will be plainly seen."
To Cope With Leakages.
[1745] "J.H." (Leyland) writes :—" Leakages of steam, water, or petrol, besides being unsightly, also are signs of waste. In -all but a few instances they can readily be cured.
. "On a steam wagon there are perhapsmany places where difficulties in this direction may be encountered. The stuffing boxes for piston rods, valve
rods, and the regulator valve spindles, for example, are frequent offenders. On those engines fitted with metallic packing, leakage from these sources is rare, but where ordinary fibrous material is used in the stuffing boxes,,neglect will readily cause trouble. If, for example, the lubrication is not attended to, the packing will frequently•bcoome burnt, or will harden, and result in a scored rlid ; on the other hand, too much cleaning of piston rods and pump plunger with metal polish is also to be deprecated.
"if trouble of this kind is encountered, all the packing should be removed, and the box and gland well cleaned. If the rods are scored, or have' shoulders formed thereon, these must be smoothed, and in exf treme cases the rod must be renewed.
The -hole in the stuffing box and gland in 'a horizontal engine frequently wears on one side and becomes -oval. To remedy this a leaden or brass washer may he fitted internally. " When cutting new packing the ends should not be cut square, hut at an angle. Each portion should be well lubricated before insertion, and the joints between one piece and the next should not be allowed to come adjacent to one another on the rod. When the hoc appears to be full, put the gland in place, and screw up gently. It will generally be found that another piece or two of pa,cking can be inserted.
"It is not necessary to screw the gland up tightly after the packing has been renewed. This only results in loss of power, bent glands and also in the rapid deterioration of the new packing from excessive friction. In the case of regulation valves, if these are correctly fitted it is pesstble to pack the gland with steam up, if the valve is stint (see sketch)."