Page 1 2 
Go
New
Find
Notify
Tools
Reply
  
Log splitter losing power
 Login/Join
 
Bernoulli
posted
I built a log splitter 2 years ago and I seem to loose power as the fluid heats up. I can go for go for about 30 minutes and then it won't split. If I wait about 45 minutes and then try to split the log it wouldn't split, it splits it. Then in about 10 minutes, it won't split.

I have tried
- Cleaning the filter. It's a reuseable filter that can be cleaned. That increased the power but still lost power after 30 minutes.
- checked the fluid level. It's still above the draw side of the tank when the motor is off
- I put new seals on the cylinder last fall. It does not sound like the fluid is running by when I try to listen to it.

Here's some specs on it:
- cylinder is 3.5 od with a 1.75' rod with a 42-44" stroke (I know, its long but it was a good deal)
- 12 hp motor
- 16 GPM 2 STAGE HYD PUMP
- Vickers control valve
- 3/8 hoses (They are that small because that's what was on the cylinder. Didn't realize I could have tapped them larger when I built it)
- AW-32 hydraulic fliud
- Filter that has a reusable filter. I was told it measures in microns.

Any suggestions would be great
 
Posts: 4 | Location: Pittsburgh PA | Registered: 13 September 2010Reply With QuoteReport This Post
Bourdon
Picture of akkamaan
posted Hide Post
quote:
Originally posted by lilpig:...loose power as the fluid heats up....

Thats why you loose power,,,oil heats up and increase internal leakage.....you have some issue that heat up your oil and/or a cooling problem
quote:
- Cleaning the filter. It's a reuseable filter that can be cleaned.

Is that a suction "filter" (strainer) or a return filter???
quote:
- I put new seals on the cylinder last fall. It does not sound like the fluid is running by when I try to listen to it.

Start from scratch one day,(cold machine) and try to track where heat is building up....(hands on is enough)...


quote:
- 16 GPM 2 STAGE - 3/8 hoses

I think this might be your main problem....max recommended oil velocity for pressure line is 25ft/sec, and the will require at least 5/8" hose at 16gpm/3600rpm...3/8" is way under sized for 16GPM (high stage)...3/8" will be fine for low stage (about 4GPM)

I think you might be under sized on the suction and the return hose too...
Here is a pdf nomogram (showing Imperial gallons) about how to estimate hose sizes...
my pic shows for 16 GPM...


quote:
- Vickers control valve
Could also be part of problem if rated less than 16GPM....do you have any details about the valve??



quote:
- AW-32 hydraulic fliud

Nothing wrong with that fluid...

This message has been edited. Last edited by: akkamaan,


Per A
...ak kam aan...flow doesn't make motion, flow is motion....
 
Posts: 1202 | Location: Port Angeles WA USA | Registered: 24 September 2008Reply With QuoteReport This Post
Boyle
posted Hide Post
Even though your piston seals in your cylinder were replaced, check to see if they are leaking. When your system is up to operating temperature, in your case ( hi temperature ) Extend the cylinder all the way to the end of its stroke. Crack the fitting on the rod side of the cylinder and then shift the directional control valve so that you are directing pressure into the piston end of your stalled out cylinder, you will see oil flowing from your rod end port if it is by passing your piston. A few drops is norm. Start there and move on to the next possibility.
 
Posts: 44 | Location: Calgary, Alberta | Registered: 12 September 2010Reply With QuoteReport This Post
Bourdon
Picture of akkamaan
posted Hide Post
quote:
Originally posted by Hydraulic Ninja:
Even though your piston seals in your cylinder were replaced, check to see if they are leaking. When your system is up to operating temperature, in your case ( hi temperature ) Extend the cylinder all the way to the end of its stroke. Crack the fitting on the rod side of the cylinder and then shift the directional control valve so that you are directing pressure into the piston end of your stalled out cylinder, you will see oil flowing from your rod end port if it is by passing your piston. A few drops is norm. Start there and move on to the next possibility.

I think that can be little mis-indicating.....when you open capped side port in the valve, the rod side will be connected to return....and some oil might drip out from return back pressure...this test is OK if rod side work port on valve or is plugged....rod side port on cylinder open....


Per A
...ak kam aan...flow doesn't make motion, flow is motion....
 
Posts: 1202 | Location: Port Angeles WA USA | Registered: 24 September 2008Reply With QuoteReport This Post
Bernoulli
posted Hide Post
Wow, thanks for all the info.

The filter is on the return.

Akkamaan, you talked about the suction line needs to be larger. Are you talking the line from the tank to the pump. That's a 1 1/2" line already

The rest of my lines are 3/8". If I change them to larger lines, the control valve and the cylinder are 3/8" female. Will I have to drill tap them larger?

Hydraulic Ninja, if it's a leak, why do I have lots of pressure when I start but then in 30 min it's down? Can the seal weaken with heat?

From what it sounds like it's getting to hot. If that's the case, is it cheaper to changes hoses or find a way to cool it (is that possible?)?
 
Posts: 4 | Location: Pittsburgh PA | Registered: 13 September 2010Reply With QuoteReport This Post
Bourdon
Picture of akkamaan
posted Hide Post
quote:
Originally posted by lilpig:
Wow, thanks for all the info.

The filter is on the return.

Akkamaan, you talked about the suction line needs to be larger. Are you talking the line from the tank to the pump. That's a 1 1/2" line already

Well, it's borderline on the nomogram... but I would'nt worry about 1 1/2" just now...

quote:

The rest of my lines are 3/8". If I change them to larger lines, the control valve and the cylinder are 3/8" female. Will I have to drill tap them larger?


You are obviously stuck with poor design from the beginning....3/8" work ports for 16 gpm is not a good match...Maybe you just oversized your pump...a 8 to 10 gpm pump would be a better match to cylinder and valve....You control valve should have at least 1/2" work ports, preferable 3/4"...You must not try to drill and tap into larger size...If your valve have 3/8" work ports, It is most likely way under sized for 16gpm...You will still benefit from larger hoses even if fittings and adapters are smaller size...(3/8")
quote:

Hydraulic Ninja, if it's a leak, why do I have lots of pressure when I start but then in 30 min it's down? Can the seal weaken with heat?

When oil heats up and get thinner (lower viscosity), and internal leakage will then increase, and create more heat....and the snow ball start rolling...

quote:

From what it sounds like it's getting to hot. If that's the case, is it cheaper to changes hoses or find a way to cool it (is that possible?)?


Cooling might eliminate the symptons, but wont elimante the cause...

Read my previous post on the thread....


Per A
...ak kam aan...flow doesn't make motion, flow is motion....
 
Posts: 1202 | Location: Port Angeles WA USA | Registered: 24 September 2008Reply With QuoteReport This Post
Boyle
posted Hide Post
For minimal amount of pressure drop while your unit is at idle that is assuming your pump is a fixed displacement type, you would want your directional control valve to have a tandem center. Meaning when your spool is spring centerd, the Pressure port is connected to the tank port, so there is minimal pressure drop through the spool back to tank. That is if that is the contributing factor to your hi temp condition. If your system idles for a long period.
 
Posts: 44 | Location: Calgary, Alberta | Registered: 12 September 2010Reply With QuoteReport This Post
Bourdon
Picture of Josh Cosford
posted Hide Post
By "loses power," do you mean doesn't have the same force or doesn't have the same speed?

Regardless, Per has all the answers. Hot oil is thinner, and bypasses more easily. Also, what is your reservoir capacity?

Ninja, I don't think I've ever seen a logsplitter with a closed centre valve; safe to say it's tandem.
 
Posts: 563 | Location: Ontario | Registered: 04 June 2008Reply With QuoteReport This Post
Bernoulli
posted Hide Post
So from what I'm understanding, I need to increase the size of my hoses. If I do that, what do I do about the control valve only being 3/8". Does that also need to be changed? That's the only unit that can't be made larger without tapping it.
 
Posts: 4 | Location: Pittsburgh PA | Registered: 13 September 2010Reply With QuoteReport This Post
Bourdon
Picture of Josh Cosford
posted Hide Post
If your valve is sized small enough that it only has 3/8" ports, than that may be too small too.
 
Posts: 563 | Location: Ontario | Registered: 04 June 2008Reply With QuoteReport This Post
Bourdon
Picture of akkamaan
posted Hide Post
quote:
Originally posted by lilpig:
So from what I'm understanding, I need to increase the size of my hoses. If I do that, what do I do about the control valve only being 3/8". Does that also need to be changed? That's the only unit that can't be made larger without tapping it.

You can not "tap" the valve into any larger flow rating...of several reasons, first enlarging the work ports, and in/out-let ports, might have negative impact on body structure, second the cores inside the valve are more restricting than the port openings, third....the spool diameter is smaller on smaller rated valves....


As I said earlier, you need to determine whats the main source of heat.... Try a laser temperature gauge


Per A
...ak kam aan...flow doesn't make motion, flow is motion....
 
Posts: 1202 | Location: Port Angeles WA USA | Registered: 24 September 2008Reply With QuoteReport This Post
Bourdon
Picture of Josh Cosford
posted Hide Post
You can get Price logsplitter valves for like, $50. Then you just need a 3/4" pressure line, and two 1/2" cylinder lines (3/4" on the cap end if you have a few extra bucks).
 
Posts: 563 | Location: Ontario | Registered: 04 June 2008Reply With QuoteReport This Post
Bernoulli
posted Hide Post
O.K. So the log splitter works when it's cold but dies when the oil gets hot. I know the conductors are too small but let's get back to basics. Oil will take the path of least resistance. If it was a cavitation problem then it would starve for oil when it's cold and work ok once it's warmed up. If this unit completely fails to split the log then you are looking for a bypass that is big enough to handle all the oil flow during the pumps high pressure cycle. That would be about 5 gpm or so. Start the unit when it's cold, shift the DCV to deadhead the cylinder. Unless you have a major seal leak this will cause the oil to flow over the relief valve. The pressure you see at that point is your relief valve setting, probably around 2500-3000 psi. As the system warms up the presure should stay constant. If the pressure drops below relief valve setting this indicates that the valve is now closed and that the oil has found an easier path to get back to the reservoir. Now start looking for hot spots other than the relief valve. If the pump is bypassing it will get hot,if the cylinder is bypassing it will get hot also.
 
Posts: 3 | Registered: 25 November 2010Reply With QuoteReport This Post
New User
posted Hide Post
Hi,
I wonder what is the status of your log splitter issues?
It will be interesting to produce a working prototype with a good size pump.
Perhaps, Veljan pump and some simple electric motor.
Do you have an interest to produce such a prototype?
 
Posts: 2 | Registered: 12 December 2010Reply With QuoteReport This Post
Bernoulli
posted Hide Post
Found out that I have to much restriction which is causing the fluid to breakdown to fast. So after about 45 minutes of working I loose power.

The solution would be to increase all my hoses, valve and fitting sizes.

Because of cost I am waiting to do that over time.

I'm not sure what you mean by making a prototype.
 
Posts: 4 | Location: Pittsburgh PA | Registered: 13 September 2010Reply With QuoteReport This Post
  Powered by Social Strata Page 1 2  
 


Copyright © 2006 Penton Media, Inc. & Hydraulics & Pneumatics magazine.