From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article reprinted from The Autocar discussing an extended experience of Houdaille shock absorbers, also known as spring checks.
| Identifier | ExFiles\Box 25\2\ Scan047 | |
| Date | 24th June 1916 | |
| A Great Appreciation of a Great Invention. Reprinted from The Autocar June 24th, 1916 Spring Checks. An Extended Experience of Houdaille Shock Absorbers on Two Cars. AS we have frequently had occasion to point out, shock absorbers, spring checks, and supplemental springs are often referred to as though the terms were synonymous. What we want to deal with at the moment is that form of shock absorber which constitutes a spring check. IT IS NOT A SUPPLEMENTAL SPRING, BUT SOMETHING WHICH CONTROLS THE ACTION OF THE ORDINARY LAMINATED SPRING. The spring makers, or many of them, maintain that any spring which requires a supplemental spring, or something in the way of a spring check for damping out its undue exuberances, is not suitable for its work, and that a spring which really is suitable should not need these complications or additions to the weight and expense of the car. This may be perfectly true, but WE HAVE NOT YET OWNED A CAR WHICH WAS NOT IMPROVED BY THE ADDITION OF SPRING CHECKS. As to the supplemental spring, there is no doubt that this also has done good work on many cars which have been fitted with unduly stiff springs in the first place, or with springs which have become stiff through neglect. The Contrast—with and without Checks. We may clear the ground by saying that we assume, therefore, that the ordinary springs of the car are as good as they can be and thoroughly well lubricated between the leaves. We assume that, given these conditions, spring checks are still a very great advantage, but so far as our experience goes, they must be of the differential order—IT IS NOT ENOUGH TO PUT A CHECK UPON THE SPRING BY MEANS OF A FRICTION ARRANGEMENT. FOR SOME THREE YEARS WE HAVE BEEN USING THE HOUDAILLE SHOCK ABSORBERS OR SPRING CHECKS ON TWO CARS, AND IN EACH CASE WE HAVE FOUND THAT THEY HAVE A REMARKABLE EFFECT UPON THE COMFORT OF THE CAR AND UPON THE EASE OF STEERING. These spring checks afford some resistance to the upward motion of the spring, and the degree in which they check its recoil can be adjusted by the simple turning of a little screw. We have tried the cars with and without these checks, and the first thing noticeable on removing them is that, if one treads on the step or jumps up and down on the floorboards, the car seems to be much more easily sprung, but directly one drives the car on the road it is not found to be the least bit more comfortable at speeds up to fifteen miles an hour, while at all speeds above that, on any but the very best roads, it is found to be far less satisfactory than with the Houdaille spring checks properly adjusted to suit the car. Various Experiments. Perhaps the worst feature of running with the uncoupled spring checks is the behaviour of THE BACK WHEELS ON ROUGH GROUND. HAVING GOT USED TO THE WAY IN WHICH THEY HAD HELD UNDER ALMOST ALL CONDITIONS, WE WERE HARDLY PREPARED FOR THE LOSS OF POWER WHICH ENSUED ON OPENING THE THROTTLE ON RATHER ROUGH GROUND TO GATHER SPEED FOR CLIMBING HILLS. HITHERTO WE HAD BEEN ABLE TO DO THIS ALMOST WITH IMPUNITY FROM THE VERY DAY WE BOUGHT EACH CAR; BUT WITHOUT THE CHECKS WE HAD FOUND WE HAD TO GO BACK TO METHODS WE HAD ALMOST FORGOTTEN AND PROCEED GINGERLY SO AS TO AVOID DANCING THE BACK WHEELS OFF THE GROUND, AND INCIDENTALLY CREATING CONDITIONS WHICH NOT ONLY MEANT BAD WEAR AND TEAR OF BACK TYRES, BUT PROBABILITY OF SIDE-SLIP. We next tested the effect of recoupling up the spring checks, but setting the adjustment screws on each one of the four so that the retardation was the same whether the spring was compressing or recoiling. This was a very great improvement as compared with no checks at all, but there was a tendency for the front wheels to bounce when meeting rather bad obstacles, such as a sudden change in road surface where the new metal was, say, an inch or so higher than the old, while the tendency for the back wheels to leave the ground with rough going, though greatly reduced, still existed. Necessity for Proper Adjustment. We knew by previous experience where the adjustment should be set for the best results, namely, roughly, halfway between the equal effect and full retardation for the back springs and slightly more for the front, and on making these readjustments each car became a different machine at once. IT WAS JUST AS COMFORTABLE AS EVER AT SLOW SPEEDS, BUT AT HIGHER SPEEDS AND MEETING ANY SUDDEN INEQUALITIES ALL BOUNCING OF THE FRONT WHEELS AND DEFLECTION OF THE STEERING WAS OVERCOME, AND THE BACK WHEELS STUCK TO THE ROAD EVEN WHEN ONE QUICKENED UP ON ROUGH GROUND FOR A CLIMB, WHICH IS PROBABLY THE TIME WHEN MOST WHEELS ARE PRONE TO JUMP FROM THE GROUND, ESPECIALLY IF THERE BE SOME SLIGHT CURVE ON THE ROAD COINCIDING. THE PARTICULAR CAR ON WHICH WE MADE THE LAST EXPERIMENTS WE HAD BOUGHT NEW WITH THE SPRING CHECKS FITTED, AND WE WERE ALWAYS STRUCK WITH THE SPLENDID WAY IN WHICH IT HELD THE ROAD, NOT REALISING TO THE FULL HOW MUCH WE OWED TO THE HOUDAILLES UNTIL WE TOOK THEM OFF. WITHOUT THEM IT WAS GOOD, BUT WITH THEM IT WAS SUPERB, and while we would be the last to deny the contention that perfect springs should not require spring checks, we can only say that up to now we have not come across these perfect springs, though we suppose they exist somewhere, that is, of course, if the spring makers are quite sure what they mean by perfect springs. The Functions of the Perfect Spring. We will not attempt to outline perfection, but we think we can safely say that the requirements of the average motorist are that his springs shall insulate him from any serious discomfort arising from ordinary road shocks, and that his wheels shall hold the road, while his car should not bounce or bounce badly if it is inadvertently driven rather too fast on wavy ground, or up or down road ledges. THE GREAT POINT ABOUT THE HOUDAILLE SPRING CHECKS IS THAT THEY ENABLE ONE TO HAVE REALLY FLEXIBLE SPRINGS WHICH GIVE EASILY TO ALL THE SMALLER SHOCKS, BUT WHICH ARE NOT PERMITTED TO DEFLECT WITH ABSOLUTE SUDDENNESS WHEN MORE SEVERE SHOCKS ARE ENCOUNTERED, AND ON THE RECOIL ARE STILL MORE FIRMLY CONTROLLED, SO THAT THE CAR CANNOT START TO BOUNCE AWAY FROM ITS WHEELS. There is no doubt, too, that GOOD SPRING CHECKS GREATLY REDUCE TYRE WEAR so far as the back tyres are concerned, as they cause the wheels to hold the road so much better. We think a proof of this is shown in our last experience, when, with a car weighing 24 cwt. without its four passengers, we have up to now covered nearly 5,000 miles without having worn out the steel-studded back tyre—a Dunlop. It is well to add that the car is possessed of very considerable powers of speed and acceleration, and, although it is not overdriven, yet, so far as hill work is concerned, it is generally put right at it, and this is probably as hard on the tyres as anything. The Houdaille Hydraulic Suspension Co., Ltd., 'Phone: Kensington 3801. 41 New Bond Street, London, W.1 Telegrams: Houdaille, Wesdo, London. | ||