powered mowers

[jac]

I have a Lynn Miller style hitch cart that I use a lot… This haytime was a real pain in the butt because my anique mower broke and I had to get a tractor neighbour in to cut the hay. My brain has been turning a few ideas over and I wondered if I could mid mount a tractor mower ?. I thought a small engine rather than land drive:o…. I know it goes against the grain but I feel a small engine is better than a tractor plus the weather over here in summer is definaitly changing.. really humid and the horses really suffered working this year and were dripping sweat doing nothing.. So… how much HP do you recon it takes to power a cutter bar of 6 or 7 ft.. thanks in advance people.. John

[Donn Hewes]

John, Have you considered adding a motor with a PTO shaft? Then there are lots of mowers you could pull, as well as other things as well. Just a thought. You will probably want a separate cart, so you will still have a forecart with out a motor. If it gets any hotter you will need to start breeding those Clydes to a jack!

[mstacy]

@jac 29491 wrote:

So… how much HP do you recon it takes to power a cutter bar of 6 or 7 ft.. thanks in advance people.. John

John, in my opinion the biggest challenge is that you are going to need at least 3.3:1 gear reduction (preferably more like 5:1) between the engine and the cutter bar. The cutter bar wants to run at about 600rpm. Small gasoline engines (Briggs & Stratton, Honda, etc) typically operate from 2000 to 3000rpm (or slightly higher). The engine won’t run at 600 rpm (and would produce very little power at that speed anyway). Conversely the cutter bar would self destruct at even 2000rpm.

Maximum power (rated value) on these types of engines is typically somewhere around 3000rpm. At lower rpm power output will also be less. A good catalog will specify what rpm the rated power is measured at. A really good catalog will provide torque and power curves (versus rpm), but that’s rare.

I recon that 2hp has been sufficient to power the cutter bar and overcome the rolling resistance of mower wheels in the grass, bar in the grass, and friction in all the other drive train components (bearings, gears, etc) for a couple generations before us. Otherwise we wouldn’t have all these wonderful MD9 mowers to fuss with. James Watt was kind enough to work out the definition of the “horse power” sometime in the 1700s or early 1800s as a way to rate his steam engines that people could intuit. I.E. how many horses can this machine replace? One horsepower is defined as 550 foot pounds per second based on his observations and calculations. But bear in mind that this value is averaged over time. A horse can certainly pull much more for short periods of time. A gasoline engine will not have that ability (unless it has a really big flywheel). Over the course of a day no horse is going to average much more than 550 foot pounds per second. That’s my story and I’m sticking to it until someone demonstrates otherwise … without resorting to steroids.

In this application the engine only has to drive the cutter bar (and the gearbox unfortunately). The horses are still employed to pull everything else (rolling resistance of the wheels, wheel bearings, draft of the cutter bar itself). So I think you’re probably going to need at least a 3hp (at 3000rpm) engine and a 5:1 gearbox. Theoretically two hp would suffice … but it would be prudent to keep a little in your back pocket for gearbox inefficiency and momentary load surges (wiry grass, meadow muffins, etc).

Good luck with this. I suspect that the motor will be the easy part. Finding/adapting a suitable gearbox may prove challenging and expensive. I look forward to seeing what you come up with.

Kind Regards,

Matt Stacy
W. Topsham, VT
USA

[jac]

Thanks for the response guys.. I had thought of a full on powered hitch cart but dont really use enough machines that need that power. If 3hp is enough then the weight is drasticaly reduced.. A couple of reductions with drive belts might be enough to reduce it to 600rpm ???..
John

[Ridge]

I&J uses a 13 hp Honda engine to power there mower. I don’t think that 3 hp would handle the mower. I have the I&J and have heard the engine labor a little even with 13hp. It is set-up with a gearbox and then a powershaft to the mower. Works great.

[mstacy]

@jac 29505 wrote:

.. A couple of reductions with drive belts might be enough to reduce it to 600rpm ???..
John

Belts are probably the simplest and least expensive way to get the speed reduction. A belt tensioner might even do double duty as a clutch like on a roto-tiller or other yard/garden implements.

Regards,

Matt

[mstacy]

@Ridge 29507 wrote:

I&J uses a 13 hp Honda engine to power there mower. I don’t think that 3 hp would handle the mower. I have the I&J and have heard the engine labor a little even with 13hp. It is set-up with a gearbox and then a powershaft to the mower. Works great.

Ridge,

The I&J Precision Cutting Sickle Mower advertisement on the web (http://www.farmingwithhorses.com/horse-drawn-haying-equipment) claims “Low torque requirement can now be ground driven”. Is this the same mower that you have?

Something just doesn’t add up here. If a 13hp engine is struggling to run the cutter bar then one of two things is going on:
Not enough speed reduction (motor running way below the rpm at which it makes 13hp) or
Two flesh & blood horses wouldn’t stand a chance at powering this cutter without an engine

Does the engine run pretty fast or is it lugging along near idle? Is there a lot of friction in the cutter bar or can you turn this thing freely by hand like with a well maintained ground driven unit?

Regards,

Matt

[jac]

Matt I figured on one of the belts being on a tensioner that could be pulled out of drive with a lever.. That 600hp combine I was on in the summer was driven mostly with belts so I recon a mower shoul be no probs.. thank everyone for the imput…
John

[mitchmaine]

hey john, maybe you could steal a pitman with the wrist pin and flywheel off an old mower. then drive the flywheel with your belts. the flywheel would add some heft and get you through some heavier grass you might not have too, and maybe reduce the need for so much hp. those old 8n fords were around 23hp. and most of the power was invested in moving tghe machine and powering a hydraulic pump fpr the lift arms. you could put an idler pulley on the belts for the clutch mech. and tighten it with a foot pedal. a deadman, so if you had to jump off the machine for something the mower would just stop on its own. i like donns idea about a dedicated hitch cart especially if the motor has to be so big and expensive. good idea and best wishes with your progress with it. keep in touch and let us know how its going.
mitch

[jac]

I like the idea of a dedicated hitch cart too Mitch but its back to this {and a lot of other} old horsemans problem.. lack of money. A good tractor mounted mower is around $1000 over here and then id have to build the hitch cart with the engine.. someday for sure but for now I will have to settle for the small engine. best regards
John

[Ridge]

Mstacy,
It is not a thing where the engine labors all the time but in thick tough grass the engine can be heard to work a little. The mowers are actually what I&J used before this german mower. I think they are an Italian made mower with guard and knives both reciprocating. A real good mower. The team I use to mow with move along at a fast pace also so that makes for more effort with the engine, I personally think the engine could be smaller than 13hp but definitely do not think a 3 hp would do it. I would not want to go any less than 8 judging by the 13hp we have. We have 2 of these mowers so my wife and I can mow at the same time and get a good amount mowed. For some reason one does seem to run harder than the other and also used more gas. Both do a great job of mowing. Ridge

[mstacy]

… @mitchmaine 29557 wrote:

you could put an idler pulley on the belts for the clutch mech. and tighten it with a foot pedal. a deadman, so if you had to jump off the machine for something the mower would just stop on its own.

That deadman clutch is a brilliant idea! If that feature had been designed into the original McCormick Deering and other mowers there would probably be far fewer folks counting with their toes.

[Y 4 Ranch]

Well we’ve done an impressive project very related to your situation. We picked up a Kosch double 7 foot mower off of http://www.auctiontime.com 2 weeks ago for $300, real bargain! Just had to be picked up in Sheridan WY, done deal there, BEAUTIFUL town to see. We hooked it behind a Pioneer with a 24-25 hp gas engine; MAN CAN WE CUT HAY!!!! 4 abreast and to town we shall go with bells on, vibration through the pole was handled by a dolly up front. If you want production work on finding this set up. Look for more in the future including pictures.
I was by myself cutting so I couldn’t get any taken.
Mike

[jac]

Mike Im taking it that you have a 2 wheeled hitch cart.. Im wondering how they cope with the weight on the 3 point linkage ?.. I am slowly comming round to the idea of a powered cart.. John

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