thum on a takuchi tb016

[ronbourd]

new to this forum,can someone familiar with takeuchi tb016 ser tb005458 tell me how to reduce the pressure on the auxilliary circuit for the installaton of a hydraulic thum. the pressure of the main circuit of the excavator is at 2875psi .with the thum cylinder I plan using,I neen around 1500psi max. can I install an overload valve on the main control? do I need to add an other hose on the boom? thank you for the reply ron

 

[J_J]

Just add a relief valve across the thumb cyl, and reduce the pressure relief,

The relief valve can relieve at about 1500 to 3000 psi.

 

[ronbourd]

J"J thanks for your reply ,but what would happen when the bucket cylinder would compress the thum cylinder,because of the volume of the rod of the thum cylinder ,would a relief valve become an overload valve? where would the oil go to ? thank you for all your help ron

 

[J_J]

That is a problem if the cyl have the same bore, as they will try to compete with each other.

If the thumb cyl is smaller it probably can not over power the bucket , unless there is a mechanical advantage somewhere..

If the bucket cyl is over powering the smaller, the thumb cyl will need a relief and that is achieved with a double relief valve.

Surplus Center - 1/2 NPT 30 GPM 1500-3000 PSI HYD CUSHION VALVE

Use to stop or minimize surge, shock and overload in hydraulic circuits

A work port relief would also work. Some valves have them.

If you dial the relief pressure to 1500 psi, it will relieve to the other side of the cyl.