Rebuilding a 7-Sweep Horsepower Unit
Rebuilding a 7-Sweep Horsepower Unit
Five teams giving the horsepower unit its first practice run.

Rebuilding a 7-Sweep Horsepower Unit

by Khoke and Ida Livingston, with William Livingston, of Davis City, IA

About a mile north of us, Khoke’s grandparents, William and Dorothy, live in a little stone-faced cob house. Now nearly 80, one would think they would sit back for a little easy living. Yet every day of the week finds them working on one project or another.

Unable to work the long hours he used to, William still works an average of 6-7 hours a day in one of his shops. Affectionately called “Grandpa” by all who know him, even by the local Amish. Most days of the week find him either in the machine shop, blacksmith shop or the woodshop. Among those who find themselves busier post-retirement, William has probably rebuilt, fixed and set up hundreds of pieces of machinery.

Not shy to recruit assistants in his shop(s), many a volunteer has learned what it meant to be “grandpa’ed.” This is when he sends you to one of his other shops for a hammer or some other tool. You are hardly out of the building before he is too impatient to wait. So, he picks up a wrench to hammer the part in place or figures out how to substitute the tool. Meanwhile the volunteer comes back with a tool now no longer needed. Congratulations, you have been “grandpa’ed.”

Last year he dedicated a few months to the completion of a long-anticipated project, the rebuilding of a 7-sweep horsepower unit. Long interested in the idea, he asked a 2nd generation horse equipment dealer in Kansas to look for one. The dealer said he had never seen one, nor had his father from whom he acquired the business. But they agreed to look out for one.

A few weeks later they called. It just so happened, one of their neighbors was having a farm sale and had an old 7-sweep in his fence row. A little startled to find one so near to home the dealer called William. The dealer bought it for $350 and William brought it home for $500. This was a little over 20 years ago. Life happens and work gets in the way and it wasn’t until last year that he got around to seeing its completion. A great post?-Covid project.

Rebuilding a 7-Sweep Horsepower Unit

What is a 7-Sweep Horsepower Unit Anyway?

Once upon a time there were no gas (or steam) powered motors. Necessity begets innovation and every discovery simply lays the foundation for the next. Mechanization arose, yet for a long time the only power sources were a person’s two hands or the four legs of a draft animal. An under appreciated amount of hand and draft powered machinery came to be.

Among these were horsepower units. A set of gears set in motion by a draft animal walking a circular track pulling a tongue. A “sweep” is the tongue. A single sweep horsepower unit has one tongue. A double sweep has two tongues, a 3-sweep likewise then has 3. William has a sampling of horsepower units in various sizes.

Rebuilding a 7-Sweep Horsepower Unit

Each sweep can be pulled solo or by a team. Single and double sweeps are most common, 3- and 4-sweeps are not too scarce. Relatively speaking. A 5- or 6-sweep is scarce and a 7-sweep almost unfindable. Not that you can find any of these at your local John Deere dealership.

Horsepower units, if they can be found at all, can sometimes be stumbled across at old farm sales or consignment auctions, if a person happens to recognize that pile of rusty old gears for what it is. They usually need to be rebuilt, but occasionally one will get lucky and all it needs is greased well.

Rebuilding a 7-Sweep Horsepower Unit

The 7-sweep horsepower units came along late in the life of horsepower unit popularity. There are not many of them out there. By the time the 7-sweeps were being developed, the growing popularity surrounding the steam engine sounded a death knell for these horse powered gears. They all but disappeared into catch-all fence rows and later scrap metal piles.

There were 3 sizes of 7-sweeps made, W-12, W-14, W-16. The number refers to the number of teeth on the gear controlling the tumble rod. William’s is a W-16.

Rebuilding a 7-Sweep Horsepower Unit

Getting Started

To his personal library, William added a copy of The Science of Successful Threshing, printed in 1911. He had it ordered off of Amazon and paid handsomely for it last year at the beginning of the project. It covers Case threshing machines, steam engines, and even happens to have a chapter on 7-sweep horsepower units. When it arrived in the mail from Washington, it had an old postcard in it where it had been used as a bookmark. The old postcard, coincidentally, was addressed to a longtime family friend’s grandfather.

Although the horsepower unit he bought was not quite complete, all of the missing parts were one of several of the same size, so a sample of each of these could be sent to the foundry to make duplicates to flesh out the necessary parts. William took body putty and built up the pieces that were worn. At the foundry they made molds for these pieces and recast the parts he sent.

The foundry charged $2.00 per pound for the castings and, about $2,800 later, William began putting the pieces together. The pieces show up as rough raw castings. He took these to his machine shop to smooth, cut, file, or drill any necessary adjustments as he went. Then each completed piece was painted to help preserve the metal and for visual appeal.

A 7-sweep horsepower unit is designed to be portable. This thought is both astounding and yet somehow logical. Most horsepower units are stationary and well secured, otherwise they can be wrenched loose and broken. Two horses with minimal exertion can operate William’s entire machine shop. How much more power is harnessed in a 7-sweep horsepower unit with 14 horses in operation? And yet it must be portable as the machinery it was designed to power was often moved, as in threshing machines and sometimes sawmills. Sawmills, namely circle saws, are stationary. But in time past, like far past, they could and would be moved from one site to another. Since then, however, log trucks were invented and moving the mill was no longer necessary.


William constructed axles and wheels to fit a frame that the horsepower unit would be bolted to. The axles were made of metal and not wood for added strength. These are stronger and less apt to bow like the wooden ones tend to do.

Rebuilding a 7-Sweep Horsepower Unit
Fixing the bull gear to the frame.

As with rebuilding any horsepower unit the place to begin is to make sure the bull gear fits the frame correctly. The bull gear is the large round gear to which everything else fits. Once the bull gear is in place the spur gear is next. This is the large vertical gear. With the bull and spur gears in place the rest is just a matter of assembling the pieces. At least that is what William says, as though I should know what that means.

Rebuilding a 7-Sweep Horsepower Unit
William Livingston and Kanoke Wilson putting the spur gear in place.

The shaft of the spur gear is not level. In fact, the little gear on one end of its shaft is on top of the bull gear and at the other end the gear is on the bottom. This causes the spur gear to tilt to one side a little.

Rebuilding a 7-Sweep Horsepower Unit
The caged spur gear.

The original 7-sweep had a wooden platform built over the frame and gears, this is to be able to see it in progress and make sure it can be stopped in time if something should go wrong while in operation. The rebuilt platform William made out of metal, and he added a railing for safety around its perimeter, and he upholstered a seat for comfort. The original design left out these accommodating features. Once the horses are engaged there is no space to duck back and forth to check on things. In fact, to William’s surprise and amusement he found himself quite stuck on the 7-sweep when it was in motion.

Pouring Babbitt

One day William tells me to come by the blacksmith shop and watch while he, and some others whom he was teaching, poured babbitt.


My face was as blank as my mind. I groped for context in the far reaches but found no mental references to help me comprehend what he was talking about. His brief explanations really gave me no clarity. He clearly underestimated my mechanical ignorance. I found myself pondering the only thing I knew enough to wonder over, is babbitt spelled like abbot or rabbit?

So, there I was midweek at his class for the furtherance of my education.

The evolution of machinery has produced the bearings and bushings used today. Before that, however, babbitt was used instead. Not that it is gone even now, just less common, you can still find it used in a variety of industrial equipment. It is a soft alloy used to protect the housing of machinery from a shaft or other moving parts.

Babbitt is usually, and particularly in this case, an alloy of lead, tin and antimony. Lead is a carrier for the tin. Tin hardens the alloy and causes the lead to be abrasive resistant. The antimony determines the melting point. Babbitt can come in varying ratios of each of these. Higher quality babbitt will have greater proportions of tin and antimony.

There are other types of babbitt available, and each alloy has its own formula and use. William bought his babbitt in 10 lb. ingots 25 years ago from Denmark at $14/lb. He found them difficult to find at that time, but with ecommerce as it is now, babbitt should not be so hard to find and order anymore.

You don’t want to melt an entire 10 lb. ingot every time you need to use a little. So, William recast the babbitt into smaller ingots for convenience. One way to do this is to get a miniature muffin tin and sit it in a shallow pan of water. Let there be no water in the muffin tin and do not drop hot babbitt into the pan of water, it can and will explode. Nothing like picking hot metal fragments out of one’s face to realize why safety glasses were invented. The muffin tin is dumped out when the little babbitt ingots have cooled enough to set. This does not take very long.

For the babbitt class, Ammon Weeks fired up his forge and put a few ingots in the babbitt ladle to begin heating up. William cautioned not to get the babbitt too hot as it can explode, it starts to spit and hot splatters fly out at random. We all went home with a few pox from the hot babbitt. If the babbitt is glossy it is too hot. If the babbitt rides up the edges of the babbitt ladle and tries to harden a ring, it is too cool.

While the babbitt is heating, the casing is prepared. The casing and rod are heated. Being the fact that this was midsummer, this was not too hard. Heating the metal in preparation is so that as they poured the babbitt, it wouldn’t cool too quickly. It can flow as a liquid and create a solid bearing. If it cools too quickly it can create cracks or blobs because it cools before it flows into place.

Rebuilding a 7-Sweep Horsepower Unit
Khoke blacking shaft with a torch.

At this time Khoke was “blacking” the shaft. He took an acetylene torch and burned a layer of soot onto the rod. This layer of soot is about .002 of an inch thick. The point is to create a tiny film barrier between the babbitt and the shaft. If it didn’t have this the babbitt would be cast too tightly around the shaft and create too much friction to use. In the old days a tallow candle was used to burn on the soot layer. This works too but its soot layer is only .001 in. The oil in acetylene makes a heavier coat on the shaft.

Rebuilding a 7-Sweep Horsepower Unit
Blacking the shaft.

With the rod covered in soot, the casing warmed up, and the babbitt melted, it was ready to pour. The babbitt bearing was poured in 2 stages. The top half of the bearing housing was set aside, and the bottom poured first. Before the babbitt was poured Khoke took some molding clay and blocked any escape routes the liquid alloy may try to take, around the rod on each end of the casing where the babbitt was supposed to end.

Rebuilding a 7-Sweep Horsepower Unit
Pouring babbitt.

Pouring the bottom half did not require the babbitt funnel. The babbitt was simply poured from the ladle, along either side of the rod quickly so it did not have time to harden before it was all poured. Babbitt hardens quickly. If the babbitt cools too quickly it can make a seam along the bottom. This makes a poor-quality bearing with a shorter life span.

Rebuilding a 7-Sweep Horsepower Unit
Poured babbitt with plenty of excess.
Rebuilding a 7-Sweep Horsepower Unit
Chiseling excess babbitt.

It takes very little time for the babbitt to be cool enough to set, just a couple of minutes before it is hardened enough to remove the rod. The clay is pulled off and wadded in a little ball to be used again later. If too much alloy was poured and the top edges are not flush with the casing, the excess babbitt is chiseled off.

Rebuilding a 7-Sweep Horsepower Unit
Chiseled babbitt. The edges are now flush.
Rebuilding a 7-Sweep Horsepower Unit
Babbitt sealed casing.

Now the rod is re-blacked in preparation for pouring the top half of the bearing. The rod and casing both are heated and then the rod is placed back into the casing that has already been poured. The top half of the bearing housing is set on the shaft and the seams are sealed with clay. On top of this housing are 3 holes; the center is for pouring babbitt with a hole on either side to allow entry for oil.

Rebuilding a 7-Sweep Horsepower Unit
Applying clay to block the edges in preparation for pouring.
Rebuilding a 7-Sweep Horsepower Unit
Pouring babbitt from the ladle through the funnel.

The babbitt funnel was placed over the center hole and the alloy was poured until we could see the babbitt begin to show in the oil holes. Then the babbitt hole was filled with the alloy and sealed off.

Rebuilding a 7-Sweep Horsepower Unit
Ammon Weeks using a hacksaw to cut through the babbitt to split the casing.
Rebuilding a 7-Sweep Horsepower Unit
Babbitt lining the casing.

As soon as the alloy was set the clay was pulled off and any excess babbitt was cut or chiseled off. This babbitt is saved to be remelted and then recycled for later use.

Rebuilding a 7-Sweep Horsepower Unit
Khoke cutting grooves in the babbitt with a babbitt gouge, to allow oil entry.

After making sure everything fit properly, William and Khoke cut the oil grooves in the babbitt with the gouge. He explained that they didn’t have to look pretty, they just had to allow entrance for the oil to keep the shaft lubricated. The hardened babbitt is not easy to score very deep and the gouge had to be worked back and forth to penetrate enough to make a groove.

With this babbitt bearing completed, the next was ready to begin. There were 6 sets total, four of which were on the spur gear shaft. The other two were on either side of the gear operating the tumble rod.

Rebuilding a 7-Sweep Horsepower Unit
The spur gear shaft with 4 new babbitt bearings.

Babbitt pouring tools include a babbitt ladle, funnel and gouge. The ladle and funnel have nice long handles in anticipation of splattering. The ladle has a slage guard. Slage is flotsam, it is waste or impurities in the babbitt. It usually comes from recycled babbitt, the impurities don’t melt and they float on top. This is not usually found in new babbitt ingots. One must be careful to not let the melted alloy level get low enough to let the slage pour through the slage guard and block it.

The babbitt class enriched my vocabulary but unless I find myself drafted into the blacksmith shop on another project, it is unlikely that my newfound knowledge will be put to much personal use.

Explaining the Horsepower Unit and its Companions

The 7-sweep horsepower unit has a couple of friends that help it work and also protect it. Once the horsepower unit is assembled, of course. Its operation follows like this. The horses walk in a circle on what is called the track, each team pulling a tongue. The tongues activate the bull gear which is 7 feet in diameter, actually 89” to be exact.

The bull gear has some little gears rolling along its teeth that are attached to a shaft operating the spur gear. The spur gear is more vertical than not, tipping just a little to allow its gears to run one on the upper and the other on the lower of the bull gear. Opposite these little (little being relative here) gears, are floating gears that equalize the pressure of the spur gear shaft.

Rebuilding a 7-Sweep Horsepower Unit
The spur gear reaches down to meet the gear operating the tumble rod shaft.
Rebuilding a 7-Sweep Horsepower Unit
Putting the platform on the horsepower unit.

The spur gear reaches down to turn a small gear that turns a tumble rod that activates the clutch. The clutch is necessary to engage power slowly. Cast iron gearing and instant startups with a high rpm are just not friends. Things get broken in a hurry.

Rebuilding a 7-Sweep Horsepower Unit
The clutch being assembled.
Rebuilding a 7-Sweep Horsepower Unit
Building the portable clutch.
Rebuilding a 7-Sweep Horsepower Unit
Tumble rod knuckles, one is affixed to a pto (power-take-off).

The clutch connects to a long set of tumble rods with knuckles on it which allow the shaft to fold at a couple points and continue turning. This is because the rod cannot go out straight from the clutch to the speed jack. The horses have to be able to step over this rod as they circle on the track.

Rebuilding a 7-Sweep Horsepower Unit
Putting together the speed jack.

The speed jack helps set the correct rpms for the thresher. There is a big flywheel that turns the belt operating the thresher. That belt doesn’t generally seem all that scary to be around, but let me tell you, that flywheel on the speed jack is big and it is spinning fast. You want no children and only highly attentive adults around that thing.

Rebuilding a 7-Sweep Horsepower Unit
A well-anchored portable horsepower unit.

The Setup and Practice Run

It took a day or two to get all the equipment in place and securely anchored. This means cement filled post holes with anchor rings cemented in to secure the horsepower unit and the speed jack. No one wants them to try walking off the job while in operation.

Rebuilding a 7-Sweep Horsepower Unit
Ammon Weeks setting up the speed jack in the field.
Rebuilding a 7-Sweep Horsepower Unit
William overseeing, Khoke adjusting the tension on the clutch.

Once set up, we scheduled a practice run. We only put 5 teams to the horsepower unit that day. It was going to be running the empty thresher. Even though most of the horses were already trained to operate a horsepower unit (where they operate it without a driver), this was a tighter track and these horses needed to sync with each other. The tongues had a pulley system to even the workload. The idea was that you could have light-weight and heavy draft horses pulling together and instead of making them pull the tongue weight equally, they pulled according to their strength.

Rebuilding a 7-Sweep Horsepower Unit
A view of the pulley eveners.

That is what it was supposed to do anyway. Instead, it allowed the loafers, big or small, to let the industrious carry the bulk of the work. So, between this and the fact that not all the horses had yet been trained to work the horsepower track, each team needed a person driving the horses to keep an eye on them.

Rebuilding a 7-Sweep Horsepower Unit
The horsepower unit hooked up to the threshing machine routed through the clutch and speed jack.

Later while standing unattended, one of the less experienced horses kicked up at a fly and caught her foot in her quarter strap. There were a few seconds of excitement, but nothing was hurt except for the tongue she sat on. We all left just a little earlier and wiser than we planned so the broken tongue could be replaced.

Threshing Day

A couple days later we reassembled to try out the horsepower unit on a working thresher. The horses were assembled and hooked up. We hardly had enough horses to round up to do the job. Khoke’s best team, Addie and Mary, were both on maternity leave and Khoke could not be convinced to work them. Buggy horses and draft horses alike worked side by side. We joked about asking our Amish neighbor if we could borrow a team from him. Menno would probably have humored us just to come over and watch. But we managed without.

It was easy enough to get it up to the necessary RPMs and then the thresher began to be fed with the bundles of wheat.

Watching everything from the horses to the HP unit and the thresher, William became concerned that it was too large a thresher (a 22” McCormick-Deering) to be operated by the 7-sweep. He said it was no problem running the thresher, but powering the blower on the thresher, he worried, would be too much.

So the field was finished with a gas power unit. The fellows were all disappointed that they lost a chance to do several miles worth of laps around that track with their horses in July’s shade-less 100 degree weather.

Now what?

Rebuilding a 7-Sweep Horsepower Unit
Horse-powered threshing operation in Iowa in 2021.

Can a threshing machine be powered by horses? The short answer is yes.

The long answer is less simple. Khoke and William slightly disagree on this point. Set up as it was last July, it would have been a strain on both the horses and the unit. Khoke feels that simply lengthening the tongues from 14 ft to 16 ft would make it much easier on the horses, and likely the unit. It would also allow the pulley evener system to work like it should and make it harder for loafer horses to shrug their load on another. The 14 ft tongues were designed to have light horses or working Morgans activating the horsepower unit. For larger draft horses it would need to be 16 ft for a more comfortable fit.

William feels we may need to get a smaller thresher. He’d love to find one of those old wooden threshing machines. The other thing he has thought about is setting up a second horsepower unit, maybe a 3- or 4-sweep, near the thresher to power the blower separately.

Threshing machines, the history changing machines that they were, are not generally used throughout the year. Just a week or two in July usually. So, William has been thinking about putting together a sawmill that could be run by the 7-sweep. This could be run at any time of the year and there would be more opportunity to fine-tune any necessary adjustments.

If there are others out there who have and/or use a 7-sweep horsepower unit, William would be thrilled to hear from them. He can be contacted through the SFJ office.


One doesn’t necessarily rebuild a horsepower unit every day. But there is plenty of everyday machinery that does need it at times. When a person finds themselves with a broken cast iron piece, fixing it can be a pain in the neck. William has sent pieces to Cattail Foundry for years.

If the piece is worn, he builds it up with a little body putty to reshape the worn places. Cattail Foundry does a good job; and they are fairly reasonably priced. But shipping and freight charges these days can really make a person wince.

Cattail Foundry
Benjamin King
167 W Cattail Rd.
Gordonville, PA 17529

Cattail Foundry is an Amish business. They do have a phone, but it is a message phone, just leave a message for them to call you back.

Practically Speaking

Is having a 7-sweep horsepower unit practical? Once upon a time it would have been. In the day when a person and all their neighbors had horses and they came together with their resources, time, labor, and draft power to knock out a big job. But today, to an independent small farmer, not really. It would be more work than use, not to mention maintaining 14 horses, especially horses broke to horsepower work at that.

It is all doable, but best done amid the conditions that birthed its invention in the first place. When people needed each other as neighbors, and as neighbors worked together to accomplish a task. This is not independence, or codependence. It is interdependence, the only road to a practical expression of true sustainable living.

Rebuilding a 7-Sweep Horsepower Unit