Log splitter will only split at low engine RPM
- Thread starter nezwick
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil. -
Super Cedar firestarters 30% discount Use code Hearth2024 Click here
Warning: Blunt, opinionated post follows....
What I am currently reading is the over complication of what should be a simple hydraulic circuit and I don’t see a real world advantage to it. Re-using the clutch portion is interjecting a variable that is not needed and isn’t gonna bring much to the real world of splitting wood.
I see the best option for long term, albeit a bit pricey, is to take advantage of the 18hp you currently have and match that to a 28GPM 2 stage splitter pump through the typical lovejoy connectors. And I know this has been touched on (but all too lightly in my opinion) but the cylinder being used needs to go. Its dangerous. Simply not designed to take typical splitter hydraulic pressures. Get a 5” bore and combine that with the 18hp and 28 GPM pump and you will have a monster.
Just one dudes opinion.
What I am currently reading is the over complication of what should be a simple hydraulic circuit and I don’t see a real world advantage to it. Re-using the clutch portion is interjecting a variable that is not needed and isn’t gonna bring much to the real world of splitting wood.
I see the best option for long term, albeit a bit pricey, is to take advantage of the 18hp you currently have and match that to a 28GPM 2 stage splitter pump through the typical lovejoy connectors. And I know this has been touched on (but all too lightly in my opinion) but the cylinder being used needs to go. Its dangerous. Simply not designed to take typical splitter hydraulic pressures. Get a 5” bore and combine that with the 18hp and 28 GPM pump and you will have a monster.
Just one dudes opinion.
I guess it would make a lot of sense to adapt to a common pump standard in order to keep this thing viable and "future proof", instead of being stubborn and trying to find an obscure part/solution like usual.
I bet the neighbor down the road could build me an adapter pretty quickly, and I wouldn't see it costing too much. My brother could do it too, but he's generally too busy with his other job.
Another possibility is that the 4 bolts which hold the present SAE B flange onto the clutch are a standard "small engine" pattern. If that's the case, a kit like the one pictured below would bolt right on, with only a small shaft extension needed to bring the Lovejoy couplers together in the middle. I will have to measure the bolt spacing. Using Lovejoy would also solve the issue of mis-matched shafts.
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/51jvvkqnqtl-_sx425_-webp.224361/ "[Hearth.com] Log splitter will only split at low engine RPM")
At the very least, I'm hoping to hear back from the hydraulic shop today with their pump recommendation so we can discuss.
I bet the neighbor down the road could build me an adapter pretty quickly, and I wouldn't see it costing too much. My brother could do it too, but he's generally too busy with his other job.
Another possibility is that the 4 bolts which hold the present SAE B flange onto the clutch are a standard "small engine" pattern. If that's the case, a kit like the one pictured below would bolt right on, with only a small shaft extension needed to bring the Lovejoy couplers together in the middle. I will have to measure the bolt spacing. Using Lovejoy would also solve the issue of mis-matched shafts.
At the very least, I'm hoping to hear back from the hydraulic shop today with their pump recommendation so we can discuss.
I hear ya, Jags. I'm already on the lookout for the correct cylinder!
I want to keep the clutch. The engine is already a sluggish and cold blooded lump to start in the winter, and having the ability to disconnect the load during engine startup/warmup really made a difference the few times I actually got to use the thing.
I want to keep the clutch. The engine is already a sluggish and cold blooded lump to start in the winter, and having the ability to disconnect the load during engine startup/warmup really made a difference the few times I actually got to use the thing.
I get it. Sometimes I do things just to see if I can do them. When it comes to hydraulic splitters and the brute force that comes with the territory I prefer the simplistic, over engineered, KISS approach. Make it as simple as possible and as reliable as gravity. And gravity is pretty reliable.
Ashful
Minister of Fire
Agreed, but there is one reason I withheld my thoughts on ditching that clutch. I don’t see electric start on there, and pull-starting a 28 GPM pump in cold weather is going to take Herculean strength. If the engine has a starter, which you can plug into the tractor for 12V supply, then definitely ditch that clutch.
I really want to keep the clutch, but I suppose I shouldn't completely rule out eliminating it. I'll have to find out what's behind it, and what the mounting pattern is on the engine block.
It's always nice to eliminate one more point of potential failure, and to simplify the machine, but the clutch is a pretty cool feature that most splitters don't seem to have.
It's always nice to eliminate one more point of potential failure, and to simplify the machine, but the clutch is a pretty cool feature that most splitters don't seem to have.
VirginiaIron
Minister of Fire
Personally, I like the flange that is square or rectangular. I think it gives greater access to the couplings when needed. Depending on your engine configuratio. Those flags should be easily modified for other bolt patterns.
Ashful
Minister of Fire
There’s a good reason most splitters don’t have a clutch. They’re totally unnecessary. For what possible reason would you want to keep it?
Cold weather starting (by pull rope) is the only reason I could see for wanting it, but you’ve negated that with electric start.
Heck, even my hydrostatic tractor and zero-turn mower have direct drive hydro pumps, no clutch.
Cold weather starting (by pull rope) is the only reason I could see for wanting it, but you’ve negated that with electric start.
Heck, even my hydrostatic tractor and zero-turn mower have direct drive hydro pumps, no clutch.
Perhaps that was a symptom of this particular pump going bad. I promise it started better from a cold start with the pump disengaged. With the pump engaged, it tended to stall out a few times and need more manual manipulation of the choke before it would run smoothly. With the pump disengaged, a couple strokes with the choke on, and it would fire right up and stay running. We're talking outside temps 20-30 degrees F.
Same experience with my tractor. It starts/warms up way easier in the winter with the PTO disengaged first even if nothing's connected to it. If I forget to disengage the PTO, holding down the clutch helps too. Especially when it's around 0 degrees F (plowing snow). The hydraulics bog it down when cold.
Though now that I think about it, our hydrostatic garden tractor doesn't seem to have an issue. Then again it's 50+ years newer and has electronic fuel injection.
Same experience with my tractor. It starts/warms up way easier in the winter with the PTO disengaged first even if nothing's connected to it. If I forget to disengage the PTO, holding down the clutch helps too. Especially when it's around 0 degrees F (plowing snow). The hydraulics bog it down when cold.
Though now that I think about it, our hydrostatic garden tractor doesn't seem to have an issue. Then again it's 50+ years newer and has electronic fuel injection.
Update - just heard back from hydraulics shop. They have a Vickers PVB15 in stock they will sell me for $450 that will be a direct replacement for the one that died. It would require zero modifications, adapters, etc.
It's still technically not a log splitter pump, as we have already learned - and they don't offer anything 2-stage with the SAE B flange.
Here are the specs. If I interpret this correctly, it does 20 GPM and 2000 PSI. Seems a little under sized compared to what we're trying to achieve with 28/3000. These specifications are at 1800 RPM.
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/untitled-webp.224371/ "[Hearth.com] Log splitter will only split at low engine RPM")
Thoughts??
I'm starting to lean toward going with a proper log splitter gear pump and deal with all the adapters and possible fabrication work. I'd rather have everything bolt up and look "original", but at the same time I don't want to risk trashing a brand new pump by over-revving the engine or causing cavitation by getting the suction line redesign wrong.
However, if the PVB15 would give the power and reliability I'm looking for (again not super concerned with speed), I'm open to just buying it and sticking it back together - then moving on to other design modifications, of course.
It's still technically not a log splitter pump, as we have already learned - and they don't offer anything 2-stage with the SAE B flange.
Here are the specs. If I interpret this correctly, it does 20 GPM and 2000 PSI. Seems a little under sized compared to what we're trying to achieve with 28/3000. These specifications are at 1800 RPM.
Thoughts??
I'm starting to lean toward going with a proper log splitter gear pump and deal with all the adapters and possible fabrication work. I'd rather have everything bolt up and look "original", but at the same time I don't want to risk trashing a brand new pump by over-revving the engine or causing cavitation by getting the suction line redesign wrong.
However, if the PVB15 would give the power and reliability I'm looking for (again not super concerned with speed), I'm open to just buying it and sticking it back together - then moving on to other design modifications, of course.
Alright... I asked my wife's opinion on the matter (who has up until this point remained a neutral observer) and she says definitely go with a 2 stage log splitter pump as opposed to buying the Vickers.
[that also means I probably have permission to spend the money on the parts, hah]
So it has been decided, the quest for the perfect pump and set of adapters can begin!
If I have to lose the clutch, so be it. I hope to remove it tomorrow in order to see what sort of mounting options I have on that side of things.
[that also means I probably have permission to spend the money on the parts, hah]
So it has been decided, the quest for the perfect pump and set of adapters can begin!
If I have to lose the clutch, so be it. I hope to remove it tomorrow in order to see what sort of mounting options I have on that side of things.
Ashful
Minister of Fire
Yeah, I'd go 2 stage gear pump, for a few reasons.
1. They're engineered with log splitters in mind. They work very well in this application, and they're very cheap by comparison to the Vickers solution.
2. Lower HP requirement per max GPM, namely because it steps down to a lower GPM any time it builds > 600 psi. That means, with a 5" cylinder, it will run very fast until it sees 12,000 lb. of resistance. Then it will shift to low gear, plow thru the resistance, and immediately switch back to high gear for fast cycling.
3. It will be an overall faster system (28 GPM vs. 20 GPM).
4. It will have more power (3000 PSI vs. 2000 PSI).
5. It will be simpler, with less overall parts to fail.
6. These are pre-engineered. They tell you exactly what line and port sizes you need, or a given pump size.
1. They're engineered with log splitters in mind. They work very well in this application, and they're very cheap by comparison to the Vickers solution.
2. Lower HP requirement per max GPM, namely because it steps down to a lower GPM any time it builds > 600 psi. That means, with a 5" cylinder, it will run very fast until it sees 12,000 lb. of resistance. Then it will shift to low gear, plow thru the resistance, and immediately switch back to high gear for fast cycling.
3. It will be an overall faster system (28 GPM vs. 20 GPM).
4. It will have more power (3000 PSI vs. 2000 PSI).
5. It will be simpler, with less overall parts to fail.
6. These are pre-engineered. They tell you exactly what line and port sizes you need, or a given pump size.
VirginiaIron
Minister of Fire
Maybe the hydraulic system was extra slushy at those lower temps. I think the mod is beneficial.
So here is a picture after I removed the "B" flange.
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/img_1330-webp.224377/ "[Hearth.com] Log splitter will only split at low engine RPM")
I wonder if something like this would bolt to that (or could be re-drilled to match those holes):
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/pump_22-28gpm_coupler_bracket_combo_square_1-webp.224378/ "[Hearth.com] Log splitter will only split at low engine RPM")
I wonder if something like this would bolt to that (or could be re-drilled to match those holes):
VirginiaIron
Minister of Fire
If the diameter is right and the flange fits over the bronze bushing/cast lip that would be a start in keeping it aligned. But it appears you still need about another 1.25"- plus, to reach the inner shaft (this could be accomplished with an additional coupling welded back to back, using a similar shaft to keep them true. Also that coupling ID looks too large for that smaller internal shaft.
1. I thought your old pump was 2 holes? If so, why do we now have 4 holes?
2. You might be better off with a double plate of some sort (spacer) to keep the pump up close to the clutch.
3. I do not know how you can access the set screw for the coupling on the inner shaft.
4. What does the old coupling look like?
1. I thought your old pump was 2 holes? If so, why do we now have 4 holes?
2. You might be better off with a double plate of some sort (spacer) to keep the pump up close to the clutch.
3. I do not know how you can access the set screw for the coupling on the inner shaft.
4. What does the old coupling look like?
I really don’t think you’ll be very happy running the PVB 15 Open centered.
and it will be slow.
I would look at a two section gear pump with spline shaft front and add the external check valve and unloading valve. that way you get your high flow and yet everything mounts up without machining adapters
and it will be slow.
I would look at a two section gear pump with spline shaft front and add the external check valve and unloading valve. that way you get your high flow and yet everything mounts up without machining adapters
1. The pump is 2 bolt - I removed the 2 bolt flange and what you see above is the clutch housing itself (check out the pictures on page 7 for comparison).
2. I'm thinking I can just make a plate/spacer like you said that will have the bolt pattern for an A pump and the 4 bolt holes to mate to the clutch housing. I could easily make this out of wood and then have a shop make it out of metal for me.
3&4. There was no set screw for the coupler on the inner shaft. It was just slip fit and used the keyway. Basically it looked just like this, but silver in color. It may have had a set screw on the pump shaft, but I can't remember. I'll be picking it up from the shop shortly so I can show you.
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/untitled-webp.224411/ "[Hearth.com] Log splitter will only split at low engine RPM")
2. I'm thinking I can just make a plate/spacer like you said that will have the bolt pattern for an A pump and the 4 bolt holes to mate to the clutch housing. I could easily make this out of wood and then have a shop make it out of metal for me.
3&4. There was no set screw for the coupler on the inner shaft. It was just slip fit and used the keyway. Basically it looked just like this, but silver in color. It may have had a set screw on the pump shaft, but I can't remember. I'll be picking it up from the shop shortly so I can show you.
Kevin, any brands/models you might suggest based on your recommendation above? The selection out there is overwhelming. Same price point as the PVB 15 or cheaper would be ideal!
VirginiaIron
Minister of Fire
I'd still have to build a spacer adapter. My 4 bolts are 2 and 3/16" on center and it looks like the log splitter pumps are 2" on center.
This morning I did go ahead and make a prototype adapter out of plywood scraps (cheap plywood so had a lot of tearout but you get the idea). I don't have an A pump in front of me to copy that flange so I had to go based off specs from the internet.
What do you think? I think it will work just fine. There were a few clearance issues since the new flange has to be smaller than the original one - but I think I worked everything out. Obviously I'll have it made out of steel (or maybe aluminum?).
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/img_1332-webp.224418/ "[Hearth.com] Log splitter will only split at low engine RPM")
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/img_1334-webp.224417/ "[Hearth.com] Log splitter will only split at low engine RPM")
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/img_1336-webp.224416/ "[Hearth.com] Log splitter will only split at low engine RPM")
![[Hearth.com] Log splitter will only split at low engine RPM](https://www.hearth.com/talk/attachments/img_1337-webp.224415/ "[Hearth.com] Log splitter will only split at low engine RPM")
This morning I did go ahead and make a prototype adapter out of plywood scraps (cheap plywood so had a lot of tearout but you get the idea). I don't have an A pump in front of me to copy that flange so I had to go based off specs from the internet.
What do you think? I think it will work just fine. There were a few clearance issues since the new flange has to be smaller than the original one - but I think I worked everything out. Obviously I'll have it made out of steel (or maybe aluminum?).
Whose clutch? Since it has a bolt on B2 adaptor now, if they are still in business, they may offer a clutch 4 bolt to A2 adaptor instead.
Sauer/Sundstrand/Danfoss offered separate B2 to A2 adaptors, but they took a longer spline coupler to make up the space.
Eaton/Vickers might have, but usually the back plate of the pump was changed completely.
If you make the adaptor, measure the shaft lengths and sort that out. I expect your PVB15 would have been a spline shaft and splined clutch, with coupler tube in between. Usually there is a snap ring in the middle inside to control the end float of the coupler. With keyed shaft, you will need a set screw, the key shaft doesn’t take well to vibration loading and will fret out the key and keyway.
Is this cavity dry? Splines with lube run forever. Usually it is pump case oil. If not oiled, pack it with synthetic grease. Will be 1/10 the life of an oil bath, but for a splitter it should be fine.
Sauer/Sundstrand/Danfoss offered separate B2 to A2 adaptors, but they took a longer spline coupler to make up the space.
Eaton/Vickers might have, but usually the back plate of the pump was changed completely.
If you make the adaptor, measure the shaft lengths and sort that out. I expect your PVB15 would have been a spline shaft and splined clutch, with coupler tube in between. Usually there is a snap ring in the middle inside to control the end float of the coupler. With keyed shaft, you will need a set screw, the key shaft doesn’t take well to vibration loading and will fret out the key and keyway.
Is this cavity dry? Splines with lube run forever. Usually it is pump case oil. If not oiled, pack it with synthetic grease. Will be 1/10 the life of an oil bath, but for a splitter it should be fine.
It may be a Rockford clutch, they were very popular back then. You have already done most of the work to fab up an adaptor, I would continue on that route rather than try to find parts to switch the housing over. You may find that OE parts from that era could be about impossible to find.
