Control Free-Fall of Hydraulic Jack

[Speedy]

I have an application where I want to remotely variably control the speed at which a hydraulic lift falls. The weight on the lift will vary.

We currenlty have manual flow controls on the pipes from the directional valves to the hydraulic piston.

Our hydraulic supplier recommends the following;

Option A;
Put a simple electro flow control on the tank line. The easiest option, but will have to be sub-plate mounted to the side of the valve block.

Option B;
Replace the existing directional valve with a proportional one, to control speed and replace the existing check valves with 'counterbalance valves' to prevent free-fall.

My question is; what is the standard design for such applications, cherry pickers etc

To me both options look feasible!

 

[hydromech]

Both are practical solutions...if you are going to use power to lower the lift.

You say you want it to fall under gravity, that is a different ball game.

Cherry pickers used to fall under gravity but only in an emergency. Newer ones have a hand pump that is used to pump the cradle down.

It is rare to see an application where the load is in free fall, other than where energy recovery is required.

When things lower under gravity, their controlability is very erratic. Changes in temperature and viscosity can cause the load to drop faster and to overrun the control system.

If you are going to power the load down(pump it down)...option B would be the best, although the most expensive.

Some more details about the application would be nice...

Hydromech