At the World Harness Racing Championships in Sweden this year, a paper was presented by a Swedish delegate. That paper was titled, What we know about sulkies and wheels.

The paper contained a number of useful lessons for Australia on the subject of the introduction of the "modified" sulky. That type of sulky was introduced in Sweden in 1970, shortly after its introduction in America. The Swedish paper said:

"Most people certainly remember the enormous attention this sulky [the "modified"] received; how we marked an "M" in the programs in front of the horses which raced in a modified sulky."

"This sulky was thought to possess almost magical qualities, and there were certainly good reasons for this attitude."

"The success created a demand which the [traditional] Swedish producers could not meet. Many other manufacturers saw a chance of a new market. The simple construction did not require extensive prior knowledge of sulky manufacturing techniques. There were no established standards for quality or durability. The not always high quality of workmanship resulted in long-lasting and serious consequences."

Sound familiar? Virtually every time a new product is introduced into the harness racing industry in Australia, we go through the same experience of an initial flood of merchandise of varying quality, followed by a shake-out of the fly-by-night operators, and then a long-term stable market of (mostly) traditional suppliers.

"In Finland the problem had grown even worse at this time. A lot of people made their own sulkies with very bad results."

"One of the more reputable Finnish Sulky Makers built a sulky-testing machine as a means of demonstrating the quality and durability of his products. After a considerable period of trial and error, the test schedule was matched to an adequate standard of strength for sulkies in service."

"Thereby the first standards of quality for sulkies materialized. Later the testing rig was transferred to Suomen Hippos, which is today responsible for approval of sulkies that may be used on racing tracks in Finland. The STC - the Swedish USTA - have accepted the Finnish standards and, as from 1986, the same standards apply for Sweden."

The Finnish Test Rig

A pair of very strong wheels are fitted to the sulky, which is then placed in the test rig with the shafts attached to a piston which moves them up and down about eighty times a minute. The wheels rest on an eccentric drum that rotates at high speed, so that the sulky is jerked rapidly up and down.

A total weight of 124 kgs is suspended at a point 35cms back from the undercarriage. (Note that on an Australian sulky, the weight would be suspended from a point about 35 cms back from a point directly above the axle. )

After ten minutes on the test rig, the sulky is measured at two points:
1. The distance between the inner legs of the undercarriage,
2. The angle between the seat support and the vertical legs of the undercarriage.

The same measurements are taken at the conclusion of the test (ten minutes later). If there is no more than ten millimetres of variation in these measurements, the sulky passes the test and is issued with a special mark of approval by the STC.

To qualify for this mark, the sulky maker is required to mark the sulkies in consecutive numerical order, preferably at the attachment of the right shaft. Additionally, the manufacturer must provide information on the materials used in the sulky and a set of operating instructions with the sulky.

It is important to remember that these procedures only became neccessary with the introduction of the "modified" sulkies:

"To start with, these sulkies (imported U.S. Nassau and Gerald carts) achieved very large market shares in Sweden. The frequency of damage became high because nobody knew that the American producers had put a maximum weight for the driver of 85 kg (i.e; about 187 pounds) and that the sulky was a pure racing machine and, in principle, not intended for the standing start system we use in Sweden, nor should the sulky be used for daily training etc."

"Initially, the Swedish producers, on the whole, copied the American sulkies. As a result of this the defects on the American sulkies were transferred to the Swedish ones."

Of course neither the Swedes or the Americans would long tolerate sulkies with such a short service life, and manufacturers in both countries eventually improved their sulky's durability, albeit at the cost of some increase in weight. However, the modified sulky is, by its very design, perennially subject to catastrophic failure.

The Swedish experience should be a caution to Australian administrators:

"The modified sulky is, essentially, constructed of only one tube, which makes it vulnerable to damage and stress fractures. On the conventional sulky there are a lot of components that can prevent catastrophic failure in the event of a failure of one part. from reports submitted to the STC it can be concluded that specific sites are especially vulnerable. These areas, which require detailed examination (irrespective of brand), are:"

"1. attachment of seat support to the undercarriage
2. attachment between shaft and wheel stay
3. attachment of shaft to undercarriage
4. where the outer leg of the undercarriage is the main structural member, the join of the inside leg to the undercarriage."

It does not seem to have occurred to either the Swedes or the Americans, that a modern sulky can be made with more than one tube, with multiple redundancy, and of such materials, that fatigue failures, when they occur (as they inevitably will) cannot result in a catastrophic failure of a major component of the sulky. Of course you have to define what constitutes a "modified" sulky, but history is a good teacher in that regard.

Joining techniques are absolutely critical in sulky construction, and all too few manufacturers seem to be aware of the pitfalls involved in the choice of the wrong system. A sulky has no suspension system to speak of, and the whole vehicle is therefor subject to very high stress loading.

Many times over the last twenty years, manufacturers have sought to save time and money by, for example, using MIG welding instead of braze-welding on tubular steel components, or using welding instead of rivets, bolts or other fasteners.

It goes on to this day, and the inevitable result is early fatigue failure of the joint. The Swedes have also come to this conclusion:

"Normally the stress on the material is particularly strong near welds where the metals flexibility is reduced."

"When fitting and joining the parts, better safety is obtained if the components are screwed together instead of welded ."

The reader might well wonder why, since metal flexibility is limited in the vicinity of BOTH welded and screwed (or bolted, or riveted) joint, the welded joint suffers early failure where the screwed joint does not?

The reason is - as the Swedes failed to note in their paper - that the materials undergo no metallurgical change in the near vicinity of the mechanical joint. They do in the case of a welded joint, and in particular, conventional (i.e. MIG or stick electrode) welds in low carbon steels.

That is why, where welding is essential - as in the undercarriage of a typical Australian sulky - all manufacturers (except for some imported carts) use braze-welding. Braze-welding is a low temperature welding technique that does not result in significant adverse changes to the physical characteristics of the metal at or near the joint.

It was not always thus. We have had our share of careless manufacturers who have sought to cut costs by the use of inferior joining techniques. Usually, when the short service life of their products resulted in complaints from consumers, they sought refuge in the " You should only use it for racing on a smooth track" argument. Such products are still on the market, so choose your sulky with care.

Material selection goes hand-in-hand with correct joining techniques as a critical element in sulky manufacture. A lot of the problems that arise with sulky manufacture, as with many things, are summarised in the old saying "There is nothing made, that cannot be made a little cheaper, by being made a little worse."

It is not widely known that steel shafts made in accordance with Australian Harness Racing Council Specification 1. , are far and away the most sophisticated sulky shafts of any material made anywhere in the world.

This sophistication has a price, of course, but the benefits have been very substantial. They are shafts that fold up in a controlled fashion during a severe accident; that bend but never actually break during an accident; that have an exceptionally long service life; that offer superior resistance to all forms of damage; that do not warp, split, or rust; that are quick and easy to repair or replace, and that are stronger for their weight than any other metal shaft in the world.

Our Swedish friends have apparently had no experience with high strength, lightweight, riveted, stainless steel construction of shafts, and thus were led to make the rather absurd claim that:

" . . a modified sulky without wooden shafts is more or less an impossibility."

The "impossible" has an uncomfortable habit of becoming commonplace.

Wheels and tyres

"In connection with the work with the sulkies, some attention has been given to the wheels used. The investigations made by the STC led to a previously used plastic wheel that often failed in accidents disappearing from the market. Plastic wheels still exist - in other designs - and have passed tests and been used for a long time ( 1.5 years) without evidence of defects. The plastic's long-term durability is not known, but today there are no valid arguments against plastic wheels."

"During the work with the wheels, views were gathered from wheel manufacturers and other experts on this subject in Swedish trotting. Generally speaking, harness racing has not utilized experience available from other sources, and we are still rather conservative. However, it is possible to get faster wheels. Our sulky wheels are considered by experts to be oversized, although these experts are prepared to accept the fact that we, in contrast to cyclists, operate in confined situations with sideways acceleration involving high stress on the wheels. On the other hand, these experts are asking why special race wheels are not being used, with simpler (cheaper and perhaps stronger?) wheels being used for daily work and training. Tyres with a highway grip are not needed, and there are advantages using [shallow] patterned or totally smooth tyres."

The Australian experience parallels the Swedish experience - except that plastic wheels of any type are currently banned from use in racing in Australia. There is, of course, no valid reason for this bann, and it should be lifted immediately and a proper wheel test put in its place. Especially since the Swedes have done us the service of sorting the "wheat from the chaff" in respect of plastic wheels.

I believe one of the main benefits to the world's harness racing that arises from these championships is the pooling of experience that enables each member body to learn from the experiences of the others.

The single greatest lesson the Swedes have given the world being the application of the scientific method to the administration of standards of harness racing equipment. One could argue that they don't know all there is to know about sulky construction, wheels etc, but you cannot argue with their approach.

Instead of banning the use of this or that piece of equipment outright, it is rigorously tested, and the test results serve as a guide to both consumers and administrators in the selection of equipment. Thus inferior products whither and die, while superior products achieve the market share they deserve among an informed consumer group.

Generally speaking, Australia seems to have enjoyed some advantages over Sweden in the availability of outside expertise to the harness racing industry. It was in the 1950's, I believe, that Bill Freebairn introduced specially constructed lightweight racing tyres on lightweight wood rims to the Australian harness racing industry.

Bill was a racing cyclist of some note, and he modified the "single" racing tyre cyclists use, by greatly enlarging its width to 4.45 cms to compensate for the softer surface of a harness racing track. The tread was all but non-existant, and these tyres became enormously popular, so that, up to about 1975, virtually every sulky used on Sydney's Harold Park track was equipped with the Freebairn Single.

The Achilles Heel of the Freebairn single was its extreme vulnerability to accident damage. The thin-walled, high-pressure tyre was easily punctured by the impact of a horse's hoof. Once deflated, it would frequently roll off the wood rim (it was glued on with varnish), which usually led to callapse of the wheel by rim failure.

Thus the driver had to weigh the advantage of superior speed against the real possibility of catastrophic wheel collapse.

The introduction of the Japanese "Sulky Super Sports" gum-walled racing tyre, combined with the bann on wood or aluminium rims, led to the decline of the high-pressure single. Although they are still used by a number of drivers around Sydney.

Bill Freebairn did, however, apply the best principles of cycle racing to the sulky wheel, and for this he deserves full credit. The Swedish paper supports many of the principles Bill used:

"The weight of the sulky is often discussed. An overweight of some kilos has been considered annoying and a disadvantage. Often the driver's weight is not considered. The experience gained in cycling would not pay that much regard to the weight of the sulky. Here the weight of the wheel is the most important! In cycling, the ratio of significance between tyre/frame is thought to be 1:30, i.e; 1 gram on the tyre (which is farthest from the hub and consequently requires the greatest effort to rotate) is equivalent to 30 grams on the frame."

Why is it so? Because the energy required to accelerate a wheel is proportional to the difference between the squares of its initial and final speeds ("Speed" here refers to the velocity at the mean radius of the wheel), whereas the energy required to accelerate the sulky is proportional to the first power of the acceleration and the sulky/driver's mass (weight).

Some years ago, an all-aluminium disc wheel was sold in Australia with the extraordinary claim that its greater weight was actually an advantage. The makers claimed that it acted like a Flywheel - which it did, and that this was some sort of advantage - which it was not. That claim flew in the face of the experience of motor racing, cycling, and of course, the uncomfortable truths of mechanics, and eventually the wheel passed into well-deserved oblivion.

But there are valid lessons here for the future of wheel design. Excessive weight is to be avoided. If lightweight discs are available with adequate strength, use them in place of heavier discs. The Swedes had this to say about discs:

"The wheel discs are meant to offer protection from accidents. They also eliminate turbulence around the spokes as a side-effect, but then it must be noted that the discs should extend all the way to the rim, otherwise air resistance will be increased."

We in Australia universally use inner discs that finish about 60mm short of the rim, to facilitate access to the valve for purposes of inflation. Plainly the use of softer, light-weight discs that can be "flipped out" for valve access, but that extend all the way to the rim is to be preferred.

Strangely, when wheel discs were first made compulsory in New South Wales, exactly that type (i.e; full cover, light-weight) discs were mandatory. Within six months, however, pressure was brought to bear and heavier, part-cover discs were not only allowed, but - at Harold Park - virtually compulsory.

I trust that the Swedish paper will lead to a thoroughgoing re-evaluation of this policy, and that sanity may once again prevail.

The Swedes also had a few controversial (to Australians) remarks on the subject of wheel spoking techniques:

"A wheel with straight spokes is considered to be faster as it keeps its shape better when rolling. The combination of a wheel with straight spokes and a soft elastic tyre seems to give the best effect. A wheels with crossed spokes, however, could possibly give a somewhat softer ride. There is no distinct evidence for one wheel being more stable [sic] than the other. Nevertheless, a large wheel means lesser rolling resistance and it does not follow irregularities in the ground as much as a smaller one. Obviously the adjustment of the wheels is very important and wheels which track wrongly unfailingly lead to losses of energy." (emphasis mine)

This "soft elastic tyre" sounds interesting. Where do we get one? One of the disadvantages of the otherwise excellent Freebairn Single was that it had to be inflated to high pressure to keep it on the rim. It was therefor prevented from fully exploiting the potential of its soft tyre on a soft track. A tyre of similar size and wall thickness to a Freebairn Single, that is wire-beaded, and made with a radial ply beneath the tread, would be ideal for harness racing.

It is strange that the Swedes did not discuss the obvious conflict between the lower rolling resistance of larger wheels verses their higher aerodynamic drag, greater tyre weight, greater mass, and greater inertia. The last point particularly relevant to the 1:30 ratio discussed earlier.

Furthermore, the history of sulky development before the turn of the century ran the full gamut of wheel sizes up to a massive eight feet diameter racing wheel. They weren't faster then, and I fail to see that they would be faster now.

Their point regarding wheel tracking is very important. By "tracking" is meant the degree of toe-in or toe-out of the wheels. The wheels should be parallel within 10mm - measured at the tyre - for best results, and they should be checked every time a wheel is removed and replaced in the sulky.

Overall, the paper was of a very high standard, and the Swedish method of scientific testing of racing equipment is to be applauded. Indeed, if the rest of the world cannot follow suit, a case could be made for making Sweden an International centre for testing and approval. I am sure the Swedes would welcome the opportunity, since they have said in this paper:
"All information, no matter how insignificant, is of interest to us."

It is possible that we in Australia might have difficulty in both funding the establishment of a testing laboratory, and finding and paying for appropriately qualified personel to run it. Even if we could, it is likely that the costs of testing, if they were levied on the producers of goods, would considerably exceed the cost of sending the same goods to Sweden for testing.

If we assume, for the sake of argument, that Australia were to introduce the modified sulky (or something like it) in the future, it would obviously be highly desirable to avoid the Swedish, Finnish and even U.S.A. experience of a sudden rush of opportunists exploiting a temporary surge of demand.

One way to avoid such a problem would be to require all would-be manufacturers to have their products tested in Sweden, and, if they passed the test, to comply with the Swedish requirements of serial numbering the shafts, and of providing with each sulky a maintenance manual and a list of materials used in the construction of the sulky.

Thus only manufacturers (new or old) committed to the long haul, would enter the market, and consumers could buy with confidence, knowing that at least the sulky they bought was a good one.

It would also be a good idea to test one of our commonly used race carts to provide a bench-mark for comparison against both the new Australian modifieds, and the U.S. and Swedish models. I believe the average Australian sulky is very much more robust than current modified types, but only a test would gauge the difference.

This would constitute something of a quantum leap in Australian standards, but the alternatives are more costly to the consumer in the long run, and more difficult to effectively administer.

No doubt the Swedes will develop their testing procedures over time to ever higher levels of sophistication, and I look forward with interest to their future contributions on this vital topic.

Copyright James S. Walsh 1987