Keeping a cylinder from bending

[bdog]

Only way to ensure that this won't happen again is to redesign the movement mechanism so you can use a shorter ram stroke to get the full range movement you want on that mast.

Good luck.

I spent a lot of time looking at this before I designed it and really the cylinder is in the only practical location. I might be able to change it up and get a few inches (maybe 4") shorter but nothing drastic.

 

[bdog]

Here is a rough sketch of the design.

 

[aczlan]

The cylinder did not contact anything. I am interested in regulating the pressure to this cylinder only, but not the main relief as I have other cylinders and motors that need full pressure.

Sounds like you need a pressure relief valve such as those found at: Surplus Center installed on just on that cylinder


Aaron Z

 

[LD1]

If you install a pressure reg, I believe you will have to add a return line.

Pressure into the regulator, pressure out to the cylinder, and a return line to dump excessive pressure when the relief opens.

 

[bdog]

You must use stops on or in the cylinder as well as stops on the boom. Using external stops to compensate for a cylinder that has to long of a throw is a bad design. Either modifying the cylinder or the mounts so the travel of the boom and cylinder are equal is necessary.

Parts like these are available for external use, or ones can be machined to go inside the cylinder: Quality Farm Supply - Hydraulic Cylinder Stroke Controls

I was looking on the site you posted and everything I saw looks like it is designed to keep the cylinder from retracting too much? I need to keep it from extending too far.

 

[bdog]

If you install a pressure reg, I believe you will have to add a return line.

Pressure into the regulator, pressure out to the cylinder, and a return line to dump excessive pressure when the relief opens.

This may be problem. This is on a skid steer and I am not really sure where to connect the return line. I know return to "tank" but the skid steer does not have a tank connection that I am aware of. I am just working off the quick connects

 

[aczlan]

If you install a pressure reg, I believe you will have to add a return line.
Pressure into the regulator, pressure out to the cylinder, and a return line to dump excessive pressure when the relief opens.

It depends on the valve. Assuming that this is a custom machine, I would install the valve right after the valve block and tee into the "tank" line for the return line from the valve (vs installing it right at the cylinder).
Edit:
Being as this is going on a skidsteer without a tank line, the following valves should work inline between the valve and the cylinder without needing a tank line.
HOWEVER, due to the difference in volume between the base and rod sides of the cylinder, they will be limited in their usefulness when your control valve is closed (ie: they should keep you from using the hydraulics to bend the rod, but wont do much to protect it from pressure spikes if it bounces around while traveling):
1/2" valves:
1/2 NPT 30 GPM 500-1500 PSI HYD CUSHION VALVE
1/2 NPT 30 GPM 1500-3000 PSI HYD CUSHION VALVE
3/4" valves:
3/4 NPT 30 GPM 500-1500 PSI HYD CUSHION VALVE
3/4 NPT 30 GPM 1500-3000 PSI HYD CUSHION VALVE


Aaron Z

 

[LD1]

It looks like the chief WP cylinders from baileys have a max-column load equal to full 3000PSI on their cylinders down to 3" diameter in a 30" length.

And the maxim cylinder with swivel ball ends and 3000PSI is rated the same down into the 2.5" cylinder.

Possibly go that route.

The cylinder you have you say was only rated @ 6500 or so?? cause a 2.5" cylinder @ 3000 psi can deliver over 14000# force.

 

[kennyd]

I was looking on the site you posted and everything I saw looks like it is designed to keep the cylinder from retracting too much? I need to keep it from extending too far.

Yes, that's why a I wrote "on or in", since the inside of cylinders vary so much, a spacer would have to be custom machined and the cylinder disassembled to install it. Stopping the retraction is easy with the parts I linked.

I was just tying to give you the general idea.

 

[jmc]

While researching a hydraulic cylinder application, I came across some information about cylinders designed such that just before they are fully extended, the retract port is exposed so that further extension pressure just bypasses back to the reservoir. Don't know if all cylinders are designed this way but if so, your solution may be nothing more than a clevis adjustment or mounting point adjustment so that your mechanism is in place just as the cylinder bottoms out.