MOTORS AND MOTORING

Dominion, Volume 11, Issue 234, 21 June 1918, Page 9

MOTORS AND MOTORING

(By "Clutch.")

Compression Tests

Compression leakago from valvo caps, plugs, ftud the priming cocks arc readily traced, especially if tho suspected joint ja-covoral-with oil, through which too €t=cnj)intr air bubbles as tho engine, is cunning. Loss of compression is very often due to iusufJicicut clearance betweou Uio valve stouis and thoir tappets, or when the valve tappet adjustment is cut down to such a fine point as to prevent the valves from shutting down .properly on to their seats as soon as tiioir stems elongate under the influence- of neat from the engine. If worn- on theP'ston rings is suspected, the crank-case inspection platen may bo removed, when tho hissing of air past tho leaking rings will be noticed whilst tho crank-shaft is rotated slowly by hand. In tho event of tho compression proving faulty on one cylinder only when this test is applied, the leaknge may possibly be due to the rings of that particular piston having worked rouud in their grooves so that all tho gaps in tho ring are in line; but il, on,'the other hand, the compression is observed, to escape at an equally rapid rate past all the pistons, then it is more than.probable that considerable wear has taken place' on tho rings, pistons, and' cylinder bores. | Punctures. ;. ■ Undoubtedly niue out of every ten punctures are caused in the following way:—Tho front wheel passes over r nail, a piece of iron,.or other substance, and disturbs its position. If it so happens that this object rises on end, and that the back wheel strikes it fair at tho moment when the business end is pointing' towards the tyro and the other towards tho ground, the puncturing material gets n footing, so to speak, in tho rubber, and each subsequent revolution of- tho tyre presses it closer towards the vitals. If the tyre is pumped boardhard 'there is probably a tendency for the puncturing object to glance off, unless it strikes dead/true on tho trend. On the other hand, it is quite probablo that with a tyre pumped to a moderate pressure it will yield in tho surface at the point where tho impact comes and this niay the direction of such impact, so that the puncturing object is turned from its purposes, or if it does pierce' tho surface of tho rubber is diverted before it reaches tho air tube. One can only theorise, however; Overloading Solid Tyres. To hosts of truck drivers, says a motoring writer, solid tyres are apparently nothing more than chunks of.rubber fastened to the wheels—what can hurt them? They will wear out in course of time, anyway, so why bother to look alter them? These big tyres look so sturdy and rugged that they do not appear to need any special care. But ideas like this cost motor truck owners a vast sum of money in the aggregate. The severity of the performance demanded of a non-pneumatic truck tyro usually more than makes up.for'its lack of delicacy, so that reasonable care with, a truck tyre is just as essential as with a motorcar tyre. Overloading is one 'of tho great' abuses visited upon truck tyres. In some cases overloading is intentional, but in the majority of instances tho practice is carried on unknowingly or carelessly. The result is tho samo in either case. The over-strain soon breaks down the tyre,before its appointed time.' A "solid truck tyre will endure a certain strain' and not a bit more than that. ■When rubber is compressed to a certain point its compressibility censes and any pressure beyond that point causes the rubber particles to crack' and separate from each other, and the tyre is weakened so that it, becomes more .snscentible to common injuries. The life" is crushed out of the tyre, and it never resumes its former resiliency. Overloading, of course, is only one of the abuses to which truck tyres are commonly sub-l jeoted, but it is the most prevalent. Overloading is bound to increase tho cost of operation greatly, and while tho tyres are wearing awav abnormally, tho •truck itself., is depreciating at an unreasonable rate. If you must overload your truck, equip it with oversize tyres when your old ones wear out. They will be far more economical in the end.

Here and There." : The Motor-cycle Club, Limited, London, which was founded in 1901, is well known- in snorting circles as promoter of long-distance competitions, such as the London-to Edinburgh and back race, the Jarrott Cup event, London to Land's Lnd ■ani back, and London to Exeter find back, among many others, has enjoyed prosperity from its inception, and on the outbreak of war had a credit balance -of .£450. This amount was invested in war bonds'; and'so' far'back | as 1915 the committee decided that'on account of so many of the members hav: | ing joined the forces it would bo advii I aula to abandon all club events, and reduce the subscription to ss. per annum tor those members not in the national .service, and to waive it altogether for members serving ,„ the ranks. Even with tins nominal subscription, the club - ?'■ , 'i?- f w possession .of some £25 which the committee decided to invest in tank bonds.; Adverting> the- London to .Exeter contest; it is an event that was in Boxilv J i a - V r"' llea as ni nny as 200 motorcYcliats -have: participated, starting from tho metropolis,at midnight, and traversing snow-covered roads Wftj

. The average motorist, says tho Dunlon Rubber Company, does not pay enough attention to the condition of the rims m , ot r ycl ?- Morelmage results from faulty rims than most motorists realise, A dent in tho clinch fJ^J W ' "T" 7 caused "▼ Btrildng « large stone on the road, for example sets up undue pressure on tho bead or tno over O p poslte th dont> that «^M 101 l or movement of tho cover sets un a cutting action.at. this point, often remit iii?. in tho ruination of an otherwise serviceable cover.' It is no great™ to have dents in clinches of rims stra.gMened out. saving in corns Anlt^ 11 X T 7 t h6 J ah °™ or expense ■Another matter is the allowing of rust to collect under the rim clinches. ' In some instances this is so bad that it prevents beads of cover fitting properly into the clinches.,, This ncrmils It movement of the base of the cover setting up friction, which added to tho corrosive action of rust soon damages a valuable cover. Periodical inspection of rims and overhauling and putting in good clean condition inside is well worth the trouble, and at tho tiaie ensures bettor tyre service. ■There has at times been considerable dismission as to whether tho operations of electric lighting and ongine-elai-ting on motor-cars should bo carried out. by separate machines or combined in a gonerator-motor. In this connection it is interesting to learn as indicating the. current practice in the United States that out of 72 different makes of cars displayed at the recent exhibition in New York no fewer than 50 were fitted with tho double unit variety—thai; is, separate generators and molors-whilo on only 16 makes was tho simile-unit form adopted. ' In two cases the car manufacturers bnvo apparently an open mind on the subject, and on one model the one variety was adopted, and on a larger car tho other form was used. Ligliting-up time:—To-day, 4.28 p.m. Next Friday, 4.J10 p.m.