PTO VS HP RATIOS?

[hawssie]

Hello. I have a ford 9030 Versitile tractor that has front and rear PTOs and the rear has both 1000 and 540. Anyways the tractor is rated as having 116 gross hp and 102 PTO hp. Well I am adapting a Tiger mower attachment to it that normally uses a high output pump that was designed to mount directly off of the front of the crankshaft of a tractor engine. This would allow the pump to turn up to about 2400 engine rpm. At the max 2400 rpm it requires around 100 hp input to put out 58 gpm at 2750 psi.
Now for my application I have to use this (or another) pump to be driven off of one of my PTO shafts instead of the engine crankshaft.
If I use this engine driven pump off of my PTO it wont turn at any near the 2400 rpms required but at most 1000 rpms with the 1000 rpm PTO and the engine turning at 2400 rpm. At this 1000 pump rpm the pump only puts out around 24 gpm.
First I thought of using a Gearmore PTO pump but their largest 9.9 cu in. model does not put out the same 58 gpm output and only has a max of 40 gpm and at only a measly 2000 psi. So I have figured a way to get my pump to turn at the same rpms as the engine using my the 1000 rpm pto and some gear reduction. Well that brings me to a more basic question. If I add a gear ratio to my 1000 pto to turn the pump at 2.4 times will it still put out 100 hp to the pump that it requires? I am confused as to how with all the different gearing (engine at 116 hp at 2400 rpm, 1000 PTO at 102 hp at 1000 rpm and other 540 PTO at 102 hp at 540 rpm) how does the HP rating stay so close to each other. You would think the rpms and gear ratios would change the HP ratings. In my case it seems that the original 116 hp engine HP is, with factory gearing turned it down to 1000 rpms to the pto shaft and at a 102hp rating then I am with gearing turning it back to mimick engine speed but will it still be able to turn this pump requiring 100 hp at 2400 rpm?

 

[Baby Grand]

In general, when going thru a gear mesh torque divides and power remains constant (minus any inefficiency losses of the gearbox). I always thought it was strange. If you think of Power as Work divided by time it might make more sense. For example:

If you carry ten cinder blocks up a ladder in one load in one minute you are using the same power as if you carry one cinderblock up the same ladder ten times in a minute.

Jim

 

[hawssie]

I agree. I think maybe Torque would be the appropriate rating for all power ratings with tractors, esp. since most now have diesel engines. We all know a 20 Hp gas tractor sure cant pull lie a 20 hp diesel tractor but by using hp the tractors would be rated identical power ratings

 

[rbargeron]

......... I am confused as to how with all the different gearing (engine at 116 hp at 2400 rpm, 1000 PTO at 102 hp at 1000 rpm and other 540 PTO at 102 hp at 540 rpm) how does the HP rating stay so close to each other...........

The power is approximately the same - it's the available torque that's different at different rpms. In general, doubling the rpm cuts the torque in half - although each set of gears involved takes away a few percent in friction losses. Geared back up to 2400 your mid pto may only have 90-95 hp but mower performance should be ok. Full-spec torque is rarely needed - you can always drop to a lower travel gear if the crop is too dense.

 

[SPYDERLK]

Hello. I have a ford 9030 Versitile tractor that has front and rear PTOs and the rear has both 1000 and 540. Anyways the tractor is rated as having 116 gross hp and 102 PTO hp. Well I am adapting a Tiger mower attachment to it that normally uses a high output pump that was designed to mount directly off of the front of the crankshaft of a tractor engine. This would allow the pump to turn up to about 2400 engine rpm. At the max 2400 rpm it requires around 100 hp input to put out 58 gpm at 2750 psi.
Now for my application I have to use this (or another) pump to be driven off of one of my PTO shafts instead of the engine crankshaft.
[SNIP... ]
Well that brings me to a more basic question. If I add a gear ratio to my 1000 pto to turn the pump at 2.4 times will it still put out 100 hp to the pump that it requires? I am confused as to how with all the different gearing (engine at 116 hp at 2400 rpm, 1000 PTO at 102 hp at 1000 rpm and other 540 PTO at 102 hp at 540 rpm) how does the HP rating stay so close to each other. You would think the rpms and gear ratios would change the HP ratings. In my case it seems that the original 116 hp engine HP is, with factory gearing turned it down to 1000 rpms to the pto shaft and at a 102hp rating then I am with gearing turning it back to mimick engine speed but will it still be able to turn this pump requiring 100 hp at 2400 rpm?

No, not quite. You might not be able to maintain full delivery at full pressure. - - You will be adding another gearset of appox 90% efficiency to the end of the one in your tractor. [By the spec#s, the one in your tractor has 102/116 ~ 88%.] You are able to feed 102 into your auxilliary. I think you can count on at least 90HP out. Perhaps close enuf. After 1st breaking it in, I would use the absolute best lightest weight approved lubricant in the gearbox. This will give you a small increase in efficiency.
larry