Hydraulic circuit.

[gruder]

I need some advice on the correct circuit design for a hydraulic cutter--shear i am building.

All this will seem very basic to those who are familliar to hydraulic circuits but i am a bit green when it comes to this & want to make sure the circuit is correct.

Basically i have a resevoir with a gear pump on a petrol engine.
The circuit will be from the pump to a flow control valve so i can adjust the speed of the shear blades. From the flow control valve to a 12v solenoid activated directional valve & from this to a double acting ram that operates the shear blades.

The 12v solenoid directional valve will be activated by a foot pedal operated switch.

I suppose there will have to be a hydraulic filter on the return line to the resevoir as well.

Does this circuit seem ok or have i got this all wrong or left out things, bypass valves etc???

Thanks, any advice would be greatly appreciated.

 

[hydtools]

Not enough information.

I used to get paid for designing these kind of things.

Buy a log splitter and modify it.

Ted

 

[PNachtwey]

I would use the motor to charge an accumulator. This way the motor can be smaller. Without the accumulator, the motor must be sized to supply the peak power required. With the accumulator, the motor only needs to supply the average power for each stoke. The stored energy can release the stored power rapidly when opening the direcitonal control valves. This is one of the advantages that hydraulic system have over motor only systems.

 

[hydtools]

Gear pump, sized so that the engine rpm is above the engine peak torque so sytem loading pulls the engine into increasing torque.

Relief valve, to protect system components.

Flow control, three-port pressure-compensated bypassing type.

Directional valve, three position four port with cylinder spool.

Cylinder, sized to deliver the force you need.

Return filter, sized for 2 to 3 times your system flow rate with integral bypass valve and spin-on 10- or 20-micron element.

Tank, with breather-filter filler.

Foot Switch, three-position for forward-off-return.

Depending on how fast you want the shear to move and the size pump you choose, you may not need the flow control. You may be able to control the shear speed by adjusting the engine speed. Pump displacement per rev times engine speed equals system flow rate.

Ted

 

[chief]

For continuous operation, you may need a cooling arrangement for your hydraulic oil.

Offshore Engineering&Design

 

[dbaird]

Just a word of caution: Most cutting/shearing machines require two-hand trip buttons to force operator to keep hands away from the hazard while operating the foot pedal. Not knowing your particular machine I don't know if this applies or not?

David Baird

Sr Controls Designer
EET degree.
Journeyman Electrician.