Gravity Flow Hydraulics

If the fluid has to drain back through the pump, this could slow it down. If there is a drain back valve, if could be clogged. What does the plumbing look like? Or is it not visible? Can you wire the pump to run backwards, too? Has it always been slow?

This is all purely speculation on my part.

Lifting is done by the pump. For return there is a restricting orifice or a flow regulator to limit the flow back, I never heard of a return done by the pump turning back may be it will be done but not yet as far as I know.

If the flow is limited by an orifice it could be possible to use a bigger diameter but this can be dangerous since are grows proportional to the square of the diameter, this means that a small change can increase the falling speed may be too much. It is better to use several orifices in series since then the effect is limited if only one is changed.

If the flow is regulated by a flow regulator then the setting can be changed (the metering orifice can be made bigger).

Was it always so ? If not there are following possible reasons:

- oil was changed and viscosity is higher than given by original manufacturer

- dirt reduced the orifice and for same pressure drop (given by the lifted element) there is less flow through.

- was it used at higher environmental temperatures and now in winter when it is colder it returns at lower speed?

I would suggest to take steps as follows:

1-check which kind of system regulates the coming down

2-check if a filter is placed in front of it and if the filter is free of dirt

3-check if it is an orifice if it is clean or not

4-check if oil has specified viscosity.

Good luck

Nick name

I want to add that if it is a gravity return, the ram (I presume a telescopic one if travel is important) is a single acting cylinder, normally the pump is used for return with double acting cylinders but then it is not any more a gravity return.

I drive a car transporter trailer, it has the same problem, its simply because there is not enough extra weight at the front (unless a car is parked right up front)!

I open the valve and then walk up and stand as near to the front as possible.....that works for me fine......

Do not add extra weight to fix this, it will ruin the towing characteristics.......