For DRIVERS, MECHANICS & FOREMEN.
Page 25
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A PRIZE OF TEN SHILLINGS is awarded each week to the sender of the best letter which, we publish on this page: all others are paid for at the rate of a penny a ltne, with an allowance for photographs, Ali notes are edited before being published. Mention your employer's name, in confidence, as evidence of good faith. Address, D., M. and F., "The Come him Motor," 7-15, Rosebery Avenue, London, EX-. 1.
Lamps Alight.
On Saturday December 20th, light your lamps at 4.20 in London, 4.11 in Edinburgh, 4.24 in Newcastle, 4.25 in Liverpool, 4.24 in Birmingham, 4.30 in Bristol, and 5.8 in Dublin.
Some Sentinel Suggestions.
The sender of the following communication has been • awarded the las. prize this week.
{2,039] " G.M." (Manchester) writes :—" As an old and experienced user of Sentinel steam wagons and as a Sentinel enthusiast, I. nevertheless feel that the following criticisms of the construction of that wagon are of :snfficient interest to be worthy of wide and full consideration. Some of the suggestions which I put forward for improvement of the chassis are, I admit, open to criticism users themselves may quarrel with me as to their value, but as to others there is, in my opinion, no room for argument, the alterations which I advocate are really necessary. In particular, I might. point out that the first one has the support of the Manchester Steam Users' Asseeiation and of White's Injectors, Ltd. " Fig. I of the accompanying sketch [which we have had. redrawn.—En.] will serve to illustrate two of my points. One is in connection with the position of the back-pressure 'valve of the oil-pump delivery pipe. As the wagon leaves the works, this valve is placed between the boiler and the steam supply valve to the injector. The consequence is that the steam carries oil with it'through the injector to the boiler, producing a greasy scale in the boiler, to such an extent that. it shows'as a scum in the water level gauge, besides coating the inside of the injector. " We ran our wagons for two years with the injector fittings so disposed, and received adverse reports from the boiler 'inspector and the injector maker at the end of each year of working. I then shifted the back pressure valve to the new position indicated on the sketch, on the engine side of the injector, with excellent results.
"The other point which is illustrated by the sketches concerns the arrangement of the mounting of the superheater coil. If the two mountings on the boiler were at the same 'level, the superheater could be turned end for end at each yearly inspection, which would materially prolong its life.
"In Fig. 2 I show the feed-wafer heater complete. As this is arranged,'if anything goes wrong with the coil, the whole of the heater has to be removed from the chassis an& all joints broken before any repairs
can be effected. I suggest the construction outlined in Fig. 3. Here the coil, with its connection is entirely supported by a cover which is fastened! to the box by bolts (not studs). If made in this way, the only joints which would need to be broken in order to get at the coil are the inlet and outlet pipes to the coil and the cover. None of the steam-pipe -connections need be touched.
"Other points ..yvhere improvement might reasonably be made are .as follow:—
" The boiler feed pump would be improved if a little more room were allowed in the centre of the casting near the stuffing boxes, so as to allow more space for the manipulation of spanners, etc., when tightening up the glands.
"As regards the main frame, I think considerable advantage -would accrue if the channels were erected with the webs [we take it that the writer means the flanges.—ED.1 facing outwards instead of inwards If so arranged, the steering gear, spring shoe, radius rod brackets, and the holding-down bolts for the platform, would be much more accessible. This would naturally involve a little modification of the attachintents, such as those of the engine case (at the pump side). It would be necessary to make use of distance pieces of some kind.
"There is considerable room, in my opinion, for improvement in the clesignOf the firegrate. As it is arranged at present,the diiver cannot 'clinker out' without losing three-fourths of his fire, which, to say • the least, must he very bad for the boiler. In the course of four years' experience of the running of Sentinel wagons, I have never yet come across a driver who Could avoid this mishap. I think that the firegrate should be made to rise and fall vertically as a whole, so that the firebars never depart from the horizontal position.
" I think I should point out that the Sentinel has undergone considerable improvement of late, as for example in regard to the engine suspension, pump return valve, arrangement of piping, design of safety valve,' bunker capacity, etc., to mention only a few points."
Although several of the alterations suggested by our correspondent are quite good, the same does not apply to all of them. He writes, of course, without a fall knowledge of the various factors which govern design. We publish his letter, however, in the belief that it is written in all good faith, for two reasons : one, that other users of Sentinel wagons may be encouraged to write to us and either criticise G.M.'s suggestions or endorse them ; the other, that the makers of the wagon themselves may have an opportunity to publish their reasons for the details of design which are attacked. Those reasons must, in the ordinary course of events, remain a sealed hook to all hut those intimately concerned with the production of the chassis. Incidentally, we welcome letters of this kind for publication in this page, provided that we are afforded means of assuring ourselves that the writer puts forward his views in good faith, and without any ulterior objeot.—Eo.]