AT THE HEART OF THE ROAD TRANSPORT INDUSTRY.

Call our Sales Team on 0208 912 2120

A NEW DEPARTURE IN AXLES.

24th February 1920
Page 24
Page 25
Page 24, 24th February 1920 — A NEW DEPARTURE IN AXLES.
Close
Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

Which of the following most accurately describes the problem?

An American Design for which Numerous Claims are Made. By Henry Sturmey.

THE AXLES for heavy commercial vehicles in this country have, for years, become virtually standardized as regards design, one following very much on the lines of the other, with little real variation. In America, 'however, wbere the development of the motor wagon has made rapid strides during the past few years, much more originality has been shown, and development has taken a form and direction quite different from its trend here.

For one thing, the internally-geared wheel drive, originally introduced by Mercedes people (or rather by the MinesDaimler Co.), and unknownsin this country as an article of home production today, has been taken in hand by several makers and developed into a practical proposition, which bids fair, in the

to oust all competitors; whilst another line of development, which has " caught on" with commercial vehicle builders there and is still ignored by our own manufacturers, is the gearle,ss type of differential, of which there are now several different patented varieties on the market, each meeting with an increasing amount of favour. Beth these developments ate worthy the attention of our manufacturers and designers. Doubtless their&failure to appreciate these developmets is due to the fact that both principles were tried here a score or so of years ago and "went out" and, so, when their attention has been called to what is being done in America, they have been inclined to say, with a certain air of self-complacency and superiority : 'Oh! they are no good —we tried them years ago here—the Yankees have a lot to learn." But, seeing that these designs are not new in the U.S. and that they -have been in increasing use and popularity over there for the last five years it must be recognized that they are not failures, or the Americans would not go on using them. We must see, too, that designs which in their first crude form, were unsatisfactory, are capable of improvement, both in detail of design and choice of material, until a point has been reached at which they can enter the practical and successful stage fust as has been the-case with the inverted tooth chain, the sliding gear, and the magneto.

And, now, • we have a new development which, whilst combining both these axle systems, makes several interesting and important departures in what may be termed the body of the axle. It is known as the "Atlas,' and is made by a Delaware firm, who claim for it :—(a) maximum rigidity with minimum weight; (b) maximum road clearance; (c) freedom from lubrication troubles; (d) accessibility of working parts; and (e) small; reduction in bevel gears. Broadly speaking, the Atlas axle is of the double-reduction type, the reduction being first by bevel gear to the differential casing, and second by pinion and internal gear in the wheels themselves. In this lattei respect it differs from the general run of internal-geared axles in the fact that, whereas the latter carry their driving pinions at the ends of drive shafts set parallel with the axle and about on a level with it, the pinion in the Atlas axle is positioned at the highest point in the circle of the gear. As, of course, the differential casing is on the same level, a very much higher road elearauce can be arranged for, a point of considerable importance when considering lorries for building and quarry purposes, and, for export. To what extent this point has been carried may be gathered when it is stated that, in the 3-ton axle, the clearance, using a 36 in. wheel and an Atlas axle, is from 61 ins, to si ins, greater than is obtained with an ordinary worm-drive truck using a 40-in. wheel. An inspection of Fig. 1 will show how this effect has been achieved, as well as illustrate the general design of the axle. The body of the axle is a hollow malleable iron casting, of rectangular section, greater in its vertical section than in its horizontal section, that being the direction of greatest stress in load carrying. This .has the usual central aperture, into which the differential ease fits and, as will be seen, the:drive shafts run straight through it and are contained within it and carry the driving pinions at their extremities on the outside ends of the casing. It will be seen, then, that the great difference in design between this and the conventional axle here, is that it is the layshaft and net the axle shaft Which passes directly through the easing and, as will be seen in the illustration, the load is carried into the wheels by short stub axles mounted in ‘extensions .of the axle casing in a downward direction, the load-carrying line being thus eubstantially below the driving axle line. The casting, which is hollow, weighs 181 lb. for the 3-ton model and the axle spindles are of chrome-vanadium steel and, as will be seen, the spindles support the axle casing at points immediately beneath the spring saddles.

The differential is of the " Powrlock " type, enclosed in a separate air-tight cuing and is shown in Fig. 2. The small difference between the size of the crown wheels and bevel pinion is very marked. The "Powrlock " differential has, I believe, already been described in The Commercial Motor; suffice, therefore, to say

that one section is attached to each drive shaft, that both wheels are driven and that the outer wheel overruns the other on. curves.

Another special feature of the construction is the attention which is given to lubrication in the design. The differential and bevel gears are completely enclosed in a separate carrier and ran in oil, the level of which is below the centre line, and no oil or grease is carried in the housing. The•annular gear in each driving wheel runs with its lower side immersed in oil, and the pinion and the various bearings arc entirely lubricated by oil carried up from the bath at the bottom. There are no grease or oil cups at all on the'axle to require attention, but the three oil baths are furnished with plugged holes for the renewal of oil, and all working parts and bearings are completely protected in dust-proof housings, as shown and explained.

Careful attention has been paid to the means for adjusting the various bearings, the thrust bearing for the bevel pinion has a slotted adjusting ring pro. vided with effective means for locking.

Another very unusual feature of the axle is that the design. incorporates the wheels, which 'are cast in one with, the brake drums, the complete unit therefore comprising, not only the axle, with differential and brakes, as usual, but the complete wheels as well, the general assembly being shown in Fig. 3, whioh shows very clearly the position of the axle casing and differential entirely above, .instead of coincident with, the

wheel centres, the great clearance this construction provides being shown in Fig. 4, which also illustrates the twin band brakes operating in the wheel drums; the bands are anchored at each end, full wrapping and operated by split wedges and are adjustable for wear by wedge expansion, without alteration of linkage; the outer, or service brake, being 3 ins. by 21 ins, and the inner, or emergency brake, 2 ins. by 21 ins.

Gear ratio is 9.77 to 1, which gives a lorry Speed of 12 m.p.h. with engine running at 1,094 r.p.m. The axle alone for the 3-tanner, without Wheels, weighs 732 lb. and, complete with 36 in. wheels and 5 in. dual solid tyres, 2,025 lb. Overall width 811 ins., tread 621 ins, and road clearance at differential 161 ins. The design is distinctly novel, and strikes me as being well worth investigation.

Tags

People: Henry Sturmey

comments powered by Disqus