SHOCK-ABSORBING ROAD WHEELS.
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An Interesting Wheel in Which Laminated Springs are Utilized Between the Rim and the Wheel Proper.
THERE HAVE BEEN innumerable attempts to devise a satisfactory form of spring wheel, but with few exceptions these failed ignominiously; owing to their inability to stand up to severe work for any length of time. Many utilized a considemble number of working parts, and the drive was' in most cases, taken through sliding rods, spring bolts, or similar devices, with the result that wear quickly occurred., this being accentuated by the fact, that in most designs the wheels were not protected from the ingress of -water and mud. In others no satisfactory provision was made for taking driving and braking stresses; the former are considerable if the wheels are used on a vehicle provided with a fierce clutch or condreeted by a negligent. driver; the latter may be severe enough to cause the rear wheels of a vehicle to lock, thes throwing great stresses on those portions of the wheels positioned between the brake drums and the road.
Some of the spring wheels were made heavy enough tb stand up to-the work for a considerable period, but in these most of the weight was unsprung, and the momentum attained by the unsprung portions when the wheel passed ovee. obstructions on the road, or into potholes, could not be damped out efficiently, and consequently the shocks transmitted to the chassis were, in many eases, quite as great as when wheels of the ordinary type were employed.
A shock-absorbing wheel which presents many pobits of interest, and which appears to have overcome the faults we have enumerated is the L.H.B., marketed by H. J. Hardy, 13, St. Helen's Place, London, E.C. 3. In this wheel a number of laminated steel springs are inserted between the wheel pis-41er and the rim carrying the solid rubber tyre. Each spring is carried in a clip spigoted into the wheel centre and held in position by a bolt. The rim carrying the tyre_ is forced into position over the springs, so that, even when the wheel does not beat on the road, the springs are under con
siderable initial compression. This is sufficient. to hold them firmly in positicein the clips, and we are assured • that even under the most exacting conditions they do not move.. . The great benefit arrived at by this construction is that the Unsprung weight of the wheel is reduced to a minimum and consists of the tyre and rim only.
It is particularly pointed out by the inventors of this wheel that they do not claim it will operate like a pneumatic tyre, but if it be used in conjunction with the solid rubber tyre it mill improve the resiliency of the complete wheel to a tremendous extent. Owing to the fact that the rim actually floats„on the springs, excessive stresses caused by letting the clutch in suddenly-, or by sudden application of the brake, causes a very slight creep of the :rim.Owing, however, to the fact that-the springs have a heavy initial load, the. friction between these and the rim is such that there can he no creep in ordinary service.
The L.H.B. wheel can be constructed for single or twin tyres; when need for the latter, each tyre and rim is separately sprung, so that a projection which, when struck by one tyre only, would, in the case of a solid wheel, lift the other tyre from the road, in this wheel merely lilts one rim. The effect of this is to give considerably better .adhesion between tyre and road, and consequently wheel spin is reduced to a minimum. . Even with the single tyre type, the springs must cause a more constant pressure to be exerted on the tyre, tending to maintain this always in contact with the road surface.
The illustrations of . these wheels for single and twin tyres show their general construction.; it will be seen that each rim is .contained between two. plates, which limit its movement sideways. The springs cannot be overstressed, as before
this can happen the inside of the rim comes into contact with the top of a spring clip, the wheel then being, to all intents and purposes, solid. The rebound-absorbing and damping properties of laminated springs are Well known; they are due to the slight friction between the plates as each moves over the other; whether the spring moves up or down; when coil, volute, or other types of springs are employed, this damping effect is absent and these springs are consequently not so satisfectery.
Owing to the slight rim slip which can take place under exceptiorel circumstances, it is claimed that L.H.B. Wheels can be employed satisfactvily on vehicles not provided, with a differential, but we should think that this statement would apply only, to the lighter types of commercial vehicles.
If the new wheel stands up well in service, does all the inventors claim for it, and proves comparatively cheap to manufacture, it should have unbounded possibilities, Particularly for the transport of thdse materials which break or deteriorate owing to vibration. Milk collected while hot from the cow, especially in warm weather, is, liable to be churned into butter before it reaches its destination if it be subjected to considerable vibration, whilst the conveyance of such articles as china, glasswsre, clocks, etc., is never devoid of risk under existing conditions.
On electric vehicles the life of the batteries depends to a great extent on the vibration to which they are, subjected, and.if this can be reduced by any Considerable a.mount, one of the most expensive Reins in the cost of running these
vehicles will.be partly eliminated. _
Shock-absoibiN wheels should 'prove of particular use on passengervehicles. This branch of the industry has recently increased so vastly that there is great scope for the introduction of means to render the passengers cemfortable, and those proprietors who own vehicles in which the comfort of the passengers is studied will certainly obtain the bulk of the trade.