The Modern Chariot (Part 2)

And so it continued right into the 20th century, where lightweight single-seat race sulkies continued the practice of using two shafts and attaching those on the sides of the horse. When a high speed vehicle was needed for two horses, they used the same pole design of heavy haulage vehicles with this result:
In the latter half of the 20th century (1969), a Project Engineer with NASA, Joseph King, re-introduced the dorsal hitch to racing with this vehicle:

The Single Shaft Sulky (“SSS”), as it was called, dramatically increased the speed of harness racers, typically by around 6 seconds over the mile. Given that a harness horse covers around 14 meters per second, horses using the SSS had a 84 meter advantage over the common race distance of one mile, or 1609 meters. The King sulky had two major performance advantages over others of its era:

1) The dorsal hitch, which offered greater animal freedom than any other hitching system, then or now, and
2) Negative balance. King placed the sulky’s combined CG well behind the axles so that the sulky tended to lift the horse by his girth strap. This reduces the load on the horse’s feet, reducing its energetic cost of locomotion, and contributing significantly to th e greater speed of the vehicle.

In 1974 all single shaft sulkies were banned, allegedly because the horse could turn under the shaft and actually face the driver, and this was held to be a potential danger in standing start races. There were many who felt that such a ban may have been somewhat ingenuous because:
a) No such incident had ever occurred in either standing start or any other type of race, and
b) If there was to be a ban on that ground, the SSS could have been restricted to the much more common mobile start races, in which the problem simply did not arise, and
c) The horse could have been fitted with a belly band and trace such that it could not turn more than, say, 30 degrees from strict fore-aft alignment with the sulky.

But King’s sulky was patented, had an overwhelming advantage over conventional sulkies, and was a definite threat to established manufacturers, so it was banned world-wide. However, not to be so easily defeated, King then created a two-shafted steel sulky with the same negative balance, calling it the “modified” sulky, and it too out-performed the neutral balance sulkies of the opposition. But negative balance had been introduced to racing in the mid 1960s by a German psychiatrist by the name of Weber. It failed to make a major impact until the SSS, but in 1974, with the banning of the SSS, everyone started making negative balance “modified” sulkies, and in the first year in which they became widely used, the number of sub two-minute miles run in the USA increased by a massive 300 per cent.