In the early 1800s, the drive to increase farm production put horses to work in treadmills. But soon even basic horse power was not enough.
As threshing machines became larger and more sophisticated, with feed and straw conveyors, as well as the new "vibrators" (or straw walkers), horse-powered treadmills could not keep up. Sweep powers were the immediate answer. It's unknown when the sweep power was introduced, but an 1836 illustration of a Gaar thresher shows a four-team sweep power driving a ground jack through a tumbling rod. A belt from the pulley on the ground jack drives the thresher.
A typical sweep power consisted of a heavy wooden frame that could be mounted on wheels for portability. A large, cast iron bull gear was mounted horizontally on that frame so it could rotate. On the bull gear were heavy sockets to which were attached wooden sweep arms. The teeth on the bull gear engaged small diameter pinion gears on either end of a cross shaft, in the center of which was a large spur gear. The spur gear turned a small pinion gear underneath the frame that drove the output shaft. A tumbling rod from the output shaft ran directly to the driven machine, or else it drove a pulley on a ground jack to which the machine was belted.
One or two horses were hooked to each wooden sweep and driven around in a circle, having to step over the tumbling rod on each round. For stability, the power was dug in, or staked and braced, to keep the whole thing from turning. To prevent problems from missteps, some operators built wooden or earth bridges. The gear reductions and the length of the sweeps were engineered to give the proper RPM at the tumbling rod, while the teams walked at a pace of 2 1/4 miles per hour.
The driver had no reins, just a whip and his voice to control his animals. In the book Machines of Plenty, Stewart Holbrook likened him to a circus ringmaster. Of course, his charges couldn't escape or attack him, being firmly attached to their sweeps, but it was his duty to keep the teams marching at a steady pace, no matter what the power demands of the thresher. With a mixture of cajolery, threats and imprecations, plus judicious flicks of his whip, the driver kept his animals to the task as he watched them go round and round and round ...
Sweep powers were built in many sizes, ranging from one-horse up to 16-horse and, although I haven't heard of any designed for dogs, goats or humans, anything was possible.
Sweep hay presses (or balers), powered by one or two horses, differed from the threshers in that the sweep was attached directly to the driven machine. With most balers, the rotary motion of the sweep was transmitted by a toggle mechanism to drive the plunger back and forth, compressing the hay until the bale could be tied. On some balers, the sweep traveled back in a semi-circle, requiring the team to be turned at each end of the arc.
Grist mills had the sweep connected directly to one of the burrs (usually the upper) and the horse, while walking around in a circle, turned the burr and the hopper. The person feeding the mill had to be alert and step over the sweep each time it came around, although some models had a platform that turned with the burr. From an account of such a mill: "We'd hitch old Dolly to the sweep, and I'd chase her round and round as John kept pouring the grindings back into the hopper, screwing down the burrs a little finer with each pass. The scoop would be held high above the hopper to blow away all the 'cornfeathers' and bran as the grindings were poured back into the hopper, over and over again, until the coarseness was all gone."
In the days before gasoline engines and electric motors, animals turned many other machines, including sorghum mills, corn shellers, buzz saws, grind stones, water pumps, cream separators, feed cutters and maybe even washing machines.
Threshing machines, steam engines, circular saw mills, horse tread powers and horse lever (sweep) powers were all offered by the Westinghouse Company of Schenectady, N.Y. in the company's 1886 catalog.
The Westinghouse lever (or sweep) powers were furnished in two sizes: No. 1 for eight, 10 or 12 horses, and No. 2 for four or six horses. Either model was available "mounted" (on wheels), or "down" (without wheels).
Prices for "down" powers, with two 10-foot sections of tumbling rod, ranged from $130 for a 4- or 6-horse model, to $170 for a 12-horse version. Wheels for a "mounted" power cost $50 more. Additional rod sections ran $6 each, while a ground jack, a device connecting the tumbling rod to a belt pulley through bevel gears, cost $20.
By 1900, the J.I. Case Threshing Machine Co. no longer offered tread powers, but they still sold 6-, 8-, 10-, 12- and 14-horse Dingee Sweep Powers (with equalizers) at $150 for the 6-horse version, up to $190 for the 14-horse. Case's 28'x50' Agitator separator (without an air stacker or self-feeder) sold for $385, so the Dingee sweep wasn't a cheap item, especially when the cost of teams was added. In comparison, a Case 12-horse steam traction engine cost $1,200 in 1900.
The 1908 Sears, Roebuck & Co. catalog advertised 2-, 4- and 6-horse sweep powers for $20.75, $28.15 and $30.75 respectively, including 20 feet of tumbling rod, three couplings, rod block, platform and a spring hitch for each sweep. The 6-horse model weighed 1,050 pounds and seems to have been a real bargain at 34 cents per pound.
The 1880s saw many improvements to threshing machines, including self feeders and band cutters, grain elevators and weighers, and wind stackers, in addition to larger and larger capacities. Each of these features demanded additional power to operate, exceeding the capabilities of even the largest sweep powers. The stage was set for the steam engine to ponderously huff and puff onto the scene, belching smoke and hot ashes - not a pretty sight for horse lovers. FC
Ever since his days as a boy on a farm in western Pennsylvania, Sam Moore has been interested in tractors, trucks and machinery. Now a resident of Salem, Ohio, he collects antique tractors, implements and related items.