Picked up half a megawatt worth of Caterpillar power, think I'll make a PTO generator

[BigBlue1]

The only time I've seen 8-10 v-belts is on a pto pump for irrigation. The belts were rather narrow and the setup was designed to handle about 80 hp. I think that you are thinking of fractional hp belts or automotive ones. There are also B,C and D sizes. A double C belt easily handled 60 hp when the above pump was run on an engine pulley setup.

Harley Davidson and other manufacturers are using toothed belts instead of chains for the final drive on their motorcycles. They have for years already. Toothed belts and serpentine belts have similar construction. I wonder what the torque is going through a Harley drive belt at full throttle in first gear?

Automotive applications went to serpentine belts for several reasons. One belt could do the same job as two or three and they are more efficient. They also take up less space for the same power requirements.

No idea about Harleys but a Victory Cross Country puts out 80+ HP to the rear wheel via a toothed drive belt (from close to 100HP engine). Also, snowmobiles use a belt drive system and routinely run well over 100HP.

In fact, what if you used a whole belt/clutch primary/secondary system from a snowmobile to power the generator? That setup has infinitely dynamic gear ratios that may allow you to overcome the initial spin-up issue and they automatically 'free wheel' when the engine goes back to idle so that may resolve the overrun clutch need.

Rob

 

[texasranger556]

No idea about Harleys but a Victory Cross Country puts out 80+ HP to the rear wheel via a toothed drive belt (from close to 100HP engine). Also, snowmobiles use a belt drive system and routinely run well over 100HP.

In fact, what if you used a whole belt/clutch primary/secondary system from a snowmobile to power the generator? That setup has infinitely dynamic gear ratios that may allow you to overcome the initial spin-up issue and they automatically 'free wheel' when the engine goes back to idle so that may resolve the overrun clutch need.

Rob

I've investigated a Salsbury clutch (snowmobile style clutch) for a leaf blower project and commonly available ones (aka: salvage/cheap) typically run 3:1 up to 1:1 or in some cases a 25% overdrive. In a generator setup you'd also need a way to fix the output RPMs of the clutch so your frequency doesn't sag when load increases.

 

[strantor]

keep in mind that if you multiply the speed by 3.33 times by gears or chain, or belts, you will see an increase of 3.33 times the amount of torque needed from the motor.. the HP requirement will remain the same.. so, direct drive is best..

The 3.33 ratio was for the tractor PTO because it wouldn't put out much more than 540 RPM. Back around post #105 I started talking about powering the generator head with a Honda motor. So that stuff about 3.33 is obsolete , at least for now, unless I change my mind and go back to the PTO power plan. For the Honda engine, I believe direct drive will be too weak. The Honda engine will need to spin a great deal more than 1800 RPM to generate enough power for the generator. I posted some dyno graphs in post #119 which should illustrate why I believe this.

 

[strantor]

No idea about Harleys but a Victory Cross Country puts out 80+ HP to the rear wheel via a toothed drive belt (from close to 100HP engine). Also, snowmobiles use a belt drive system and routinely run well over 100HP.

In fact, what if you used a whole belt/clutch primary/secondary system from a snowmobile to power the generator? That setup has infinitely dynamic gear ratios that may allow you to overcome the initial spin-up issue and they automatically 'free wheel' when the engine goes back to idle so that may resolve the overrun clutch need.

Rob

I would have to drive a few hundred miles before I start seeing any snowmobiles for sale. I prefer something with a manual transmission or otherwise some sort of fixed gear ratio. The infinitely variable contraptions are cool and well suited to traction drive applications, but for a generator application I need a consistent output RPM.

 

[BigBlue1]

I would have to drive a few hundred miles before I start seeing any snowmobiles for sale. I prefer something with a manual transmission or otherwise some sort of fixed gear ratio. The infinitely variable contraptions are cool and well suited to traction drive applications, but for a generator application I need a consistent output RPM.

OK. Well, at least there are belt setups out there that can definitely handle the HP you need here. The cycle ones are probably the best bet then because various sprockets should be easily available. Not necessarily cheap though... Those belts and sprockets can fetch bit $$.

Rob

 

[LouNY]

I punched some numbers out of curiosity; assuming your generator needs 1800 rpm for 60 cycle power.


rpm gear ratio direct rpm after 3.720 diff effective 1.86 diff
1800 1st 3.250 5850 rpm 21,762 rpm 10,881 rpm
1800 2nd 1.782 3207.6 rpm 11,932.3 rpm 5966.2 rpm
1800 3rd 1.172 2109.6 rpm 7,847.7 rpm 3923.9 rpm
1800 4th 0.902 1623.6 rpm 6039.8 rpm 3019.9 rpm
1800 5th 0.702 1263.6 rpm 4700.6 rpm 2350.3 rpm

If my spacing stays with my typing the first column is the wanted 1800 rpm for the generator, the second column is the transmission gear ratio, the 3rd column would be the engine rpm if the differential was bypassed and the output shaft of the transmission fed the generator, the 4th column is using the differential ( the differential would have to be locked so both axle shafts rotated at the same speed, ie. a lincoln locker welded pinion gears) , the 5th column would be using the open differential and locking one axle with only the other axle turning (which doubles the speed of the rotating axle, and would wear the pinion gears).
Using the engine and complete transaxle with the differential locked would have the engine at 4700 rpm to provide 1800 rpm to the generator.
Using the engine and complete transaxle with an axle locked would have the engine at 3923 rpm in 3rd gear, 3020 rpm in 4th gear to provide 1800 rpm to the generator.
If you could bypass the differential 2nd gear would be 3208 engine rpm for 1800 rpm out.

 

[strantor]

I punched some numbers out of curiosity; assuming your generator needs 1800 rpm for 60 cycle power.


rpm gear ratio direct rpm after 3.720 diff effective 1.86 diff
1800 1st 3.250 5850 rpm 21,762 rpm 10,881 rpm
1800 2nd 1.782 3207.6 rpm 11,932.3 rpm 5966.2 rpm
1800 3rd 1.172 2109.6 rpm 7,847.7 rpm 3923.9 rpm
1800 4th 0.902 1623.6 rpm 6039.8 rpm 3019.9 rpm
1800 5th 0.702 1263.6 rpm 4700.6 rpm 2350.3 rpm

If my spacing stays with my typing the first column is the wanted 1800 rpm for the generator, the second column is the transmission gear ratio, the 3rd column would be the engine rpm if the differential was bypassed and the output shaft of the transmission fed the generator, the 4th column is using the differential ( the differential would have to be locked so both axle shafts rotated at the same speed, ie. a lincoln locker welded pinion gears) , the 5th column would be using the open differential and locking one axle with only the other axle turning (which doubles the speed of the rotating axle, and would wear the pinion gears).
Using the engine and complete transaxle with the differential locked would have the engine at 4700 rpm to provide 1800 rpm to the generator.
Using the engine and complete transaxle with an axle locked would have the engine at 3923 rpm in 3rd gear, 3020 rpm in 4th gear to provide 1800 rpm to the generator.
If you could bypass the differential 2nd gear would be 3208 engine rpm for 1800 rpm out.

Thank you for taking the time to crunch those numbers! This is a front wheel drive car and the "differential" is integral with the transmission. It probably would be very difficult to tap directly into the transmission output, bypassing the differential. See the attached picture; within the transmission housing, the transmission output goes directly into a hypoid gear to the axle output. So for the time being, it seems the best options are either to come off the axle output or the serpentine belt.

With regards to the locking of one side axle to double the speed of the other side, I am aware of that scenario in RWD vehicles that actually have a differential. But does the same hold true for a FWD car? I really don't know. The "diff" internals in the attached picture don't seem large enough to be as complete as a rear diff. I was kinda assuming that I cpuld just pick one side or the other depending on what direction of rotation I need, and I wouldn't have to worry about welding any diff parts or locking the opposite side. I hope that's not an oversight on my part... someone let me know please!

 

[texasranger556]

Yes you would have to lock the diff just like a truck axle. In theory you could lock one axle to halve the ratio, but they are only designed for intermittent use so running a generator with constant load I wouldn't expect it to last very long.

My little brother liked to do one wheel burnouts in his neon, until it spit the spider gears out the bottom of the transaxle.

 

[strantor]

Yes you would have to lock the diff just like a truck axle. In theory you could lock one axle to halve the ratio, but they are only designed for intermittent use so running a generator with constant load I wouldn't expect it to last very long.

My little brother liked to do one wheel burnouts in his neon, until it spit the spider gears out the bottom of the transaxle.

Well, crap. That's inconvenient.

 

[ptsg]

What would be the inconvenient of running directly off the engine with a big ***** toothed belt? Running the engine, let's say 3500 to 4000 RPMs then reducing the speed to the desired 1800 RPM via a bigger pulley in the generator.