Gentlemen,
I work for a airline that uses older FMC loaders to load pallets onto aircraft. We have a problem with shock load when manipulating these pallets with a conveyor system using hydraulic motors. The system uses a fairly conventional series set of hydraulic motors operating at 2000 PSI and 4 Gal/Min when operating. These units are quite old and no longer supported by the manufacturer. (At least for hydraulic redesign) We would like to install some sort of hydraulic control valve that could be set up to spool the hydraulic motors up to speed instead of them coming on with a bang. We feel that an accumulator would not work in this situation because each of the motors is individually controlled by a joystick and except for the first one brought into play there would be no further action by an accumulator when the others were opened up in the series configuration. Does anyone know of a control valve that could be adjusted to control how quickly the flow was brought up to speed?... (i.e. 0 – 4 gal/min in say ½ sec instead of instantly)

Thanks
Sam

With the informaton suppled the only answer I could think of mighht be these Soft Shift valves from Eaton/Vickers.

http://hydraulics.eaton.com/products/pdfs/11-05-0001.pdf

The Sauer Danfoss PVG valve will accomplish a propotional start and stroke of the control either manually or electric

Why not use proportional valves with a dead band controlled by a joy stick that provides -10 to +10 volts to the valve. This way the operator would have control of the speed and acceleration.
The dead band would make it easy to keep the system stopped to hold position.

few years ago probably that loader is working properly. these type of equipments are really equipped with all the necessary valving to prevent shocks.

there might only be problem in either the joystick(is it really electronic controlled meaning the joystick is a potentiometer?), the proportional valve, the card , the brake valve (sometimes called the counterbalance valve) or the operator who just dont care shifting the joystick so fast rather than slow to achieve a smooth movement.

or probably the ramp time up or down potentiometers are not properly set!!!

ALTERNATETELY YOU CAL FIT VARIABLE FREQUENCY DRIVE FOR PUMP MOTOR CIRCUIT , IF ELECTRIC MOTOR IS PRESENT .

tstshutz is right. The PVG 32 valve with high proportional actuators will do the job. You don't necessarily have to use a joystick with it. You'll only need a joystick if you want the operator to have manual control over acceleration/deceleration and max speed. I have an adjustable ramping module that will take care of accel/decel for you.

Drop me an e-mail at wwo@att.net and I'll give you a price after getting a few details from you. We can likely ship a valve assembly the same day you order it.