log splitter cylinder failure

[motoman3b]

Friend suggested that, didnt see evidence of any ice from frozen water and my fluid looked clear but I suppose it could be possible.....

 

[triptester]

A combination of things may have caused the failure.
The cylinder may have had a low pressure rating.
The pump does not have a internal relief valve in the high pressure section and is capable of extreme pressures if the control valve relief fails to operate properly.
On the return stroke the sudden bottoming of the ram can cause sudden pressure spikes.
Metal gets more brittle with age and cold temps.
The tie-rods could have been over tightened increasing strain.

 

[motoman3b]

A combination of things may have caused the failure.
The cylinder may have had a low pressure rating.
The pump does not have a internal relief valve in the high pressure section and is capable of extreme pressures if the control valve relief fails to operate properly.
On the return stroke the sudden bottoming of the ram can cause sudden pressure spikes.
Metal gets more brittle with age and cold temps.
The tie-rods could have been over tightened increasing strain.

I do think it was only rated for 2500 psi and I'm not sure what my relief is set to but I do have a gauge and have pegged it out at 3k but my pump is only rated for 3000psi max, have had it stall the motor out a few times when putting a heavy load on it. The valve on this unit is an old 2 spool not sure if it has a pressure relief but I'm going to look close tonight and see and try to set it around 3k. At any rate I would think the hose would of blew way before and chunk of cast metal that thick would if it was caused by over pressure

 

[Mac88]

The fact that the casting split through the center of the inlet port lends some credence to Steve's idea that the fitting was overtightened.

 

[Fronty Owner]

I don't think that was aimed at me, but just in case.

I wasn't referring to the elbow being the problem in itself, just that someone who's not familiar with tapered NPT style threads could conceivably overtighten one to the point of stressing or even cracking the cylinder casting, causing the failure we see in the OP's pictures.

It's just an idea I have, can't say for sure without knowing more, but between that and my binding cylinder/side loading theory (that the OP's mention of having a lot of slop in the push plate leans toward), it's all I've got.

I know people that do know what they are doing with NPT and they still over tighten them. or wrap a ball of tape around the end and get two threads engagement. I dont like NPT.

Call your local prince hydraulics dealer and get a new end cap. the rest look good.

Im going with my original suspicion. you were too cold for operation. steel gets brittle in cold temperatures unless its specifically designed for the conditions.

 

[WoodTick007]

can you please post pictures of the entire splitters construction? Was the 90 degree fitting going into the front of the cylinder a black pipe fitting? What pressures were you reading on your gauge when the cylinder deadheaded? what pump, engine and engine RPM was the system setup to operate at?

 

[WoodTick007]

I do think it was only rated for 2500 psi and I'm not sure what my relief is set to but I do have a gauge and have pegged it out at 3k but my pump is only rated for 3000psi max, have had it stall the motor out a few times when putting a heavy load on it. The valve on this unit is an old 2 spool not sure if it has a pressure relief but I'm going to look close tonight and see and try to set it around 3k. At any rate I would think the hose would of blew way before and chunk of cast metal that thick would if it was caused by over pressure

The hose didn't blow because you had the NPT fitting over tightened cause the excessive stress on the casting. Your hoses are most likely rated at 3500psi Your pump is rated for 3000 psi at a certain RPM if you exceed that rpm the pump will increase in PSI. The cylinder you had was rated for 2500psi and not 3000 PSI. Your lucky you or a bystander was not seriously injured or killed.

 

[stihl023/5]

Yes I too feel Steve is right look at the picks there is a v shaped piece missing out of that inlet casting hole so it probably was stressed.

 

[Cbird14]

With the side load theory, wouldnt you think it would wear the seals before it started putting stress on the cast end? The seals were all good no sign of leakage as well with the pipe fitting if there was a hairline crack one would think it would of seeped hydraulic fluid and been pretty obvious

Here are some tear down pics

i just bought a new 4"x24" cylinder for $200 made in the usa after mine snapped the shaft off right at the yoke. it had been welded before i bought it by someome who doesnt know how to weld. just laid a bead around it and put it back on. ill post some pics of it

 

[Cbird14]

View attachment 271432
View attachment 271433sorry the damn cats head was in the way. I know I know. Don't worry. The cat got thrown.

 

[stihl023/5]

Don't throw the cat.

 

[motoman3b]

Got the fittings to adapt the old hoses to the new cylinder today welded up the pusher guide plates today to tack out the slack in the pusher plate... she's back up and running new cylinder is 3k psi think I'm good to go now!

 

[stihl023/5]

Hope everything works well for you.:msp_thumbsup:

 

[WoodTick007]

150 and 300 PSI

Just an FYI.... You keep mentioning how your pump and cylinder are rated at 3000psi... perhaps you should take a look at your fittings as they look to be standard pipe fittings. Schedule 40 black iron is rated for 150 psi and schedule 80 is rated for 300psi.

 

[motoman3b]

Just an FYI.... You keep mentioning how your pump and cylinder are rated at 3000psi... perhaps you should take a look at your fittings as they look to be standard pipe fittings. Schedule 40 black iron is rated for 150 psi and schedule 80 is rated for 300psi.

Wrought Steel Pipes - Bursting Pressure

Burst pressure of 10k I know its not advised but pipe fittings have been used on homemade log splitters and other hydraulic equipment for years so I'm not to worried about that if they didnt want you to use them I guess they wouldnt make the fitting NPT

 

[Fifelaker]

Wrought Steel Pipes - Bursting Pressure

Burst pressure of 10k I know its not advised but pipe fittings have been used on homemade log splitters and other hydraulic equipment for years so I'm not to worried about that if they didnt want you to use them I guess they wouldnt make the fitting NPT

It only taks once.injury caused by high-pressure fluid I will not use them because they are only rated @ 1300 psi. and that is a far cry from 10,000 psi.