Have you left the jack with the original 'engage the jack handle release' arrangement? I made a simple knurled knob out of a piece of scrap Ali for my workshop press; it made control of the release/reduction of pressure much easier than using the jack handle type device supplied with the press.

BTW, as you can see from the photo, sometimes 30 tons isn't enough on its own to free a stubborn rusted in part!

You could add a lever to the release valve and then operate the lever with a screw to give both control and limited movement to the release valve. I don't know what your setup is like but this type of operation would allow you to put the release operating knob in a convenient position and also avoid accidental release caused by catching the release valve operating knob.

Martin C

Perhaps allowing even more control than a knob would be adding a lever to the knob.

How does the threaded part operate the valve at its base?
If it's a tapered fit, a bit like a brake bleed nipple, then maybe a new part with a more pointed taper, such that the hole is exposed slower as the bolt is unscrewed, similar to a carburettor main jet..

Bill

If that is the jack I think it is there may well not be room to permanently fit anything sensibly easy to operate to the release valve without interfering with the actual jack operation.

If that is the case look into whether some sort of L shaped, box spanner and lever, device can be made with the initial travel limited but striking the ground or part of the jack body. Further opening would require the spanner to be removed and refitted putting the lever clear of the obstruction for another partial turn. I have encountered more sophisticated variants of that style of device which were permanent assemblies with sprung loaded detents restricting the travel to half or one third of a turn at a time. Pushing the knob down let it move past the detent for another bite.

I'm sure the same sort of thing could be arranged with a spanner device and suitably shaped head on the release screw. The bottle jack on my home made press, similar design to Sueee, has a flat bar shape on the end of the release device so restricting to half a turn at a time is easy. The T-bar handle spanner I made for the job turned out rather longer than I'd ideally have liked due to having to avoid a projection that would have restricted it to half a turn at a time!

Clive

Clive

A small clamp-on bracket on the left hand plate, a pivoting nut on that bracket, a clamp-on lever on the release valve with a pivoting anchor point at the top and a screw with knob between to two pivots and you have a controlled release mechanism for very little cost or effort.

Martin C

Is there a ball in the hole under the flat ended screw? That's sometimes done as a cheap option that is tolerant of the fluid port not being quite concentric with the thread. If port is not concentric with thread, it's more difficult to produce either a 'needle' or a 'spline' tip on any replacement item to give finer control.

All I would say is does that design put any part of you underneath the table?

Is it wise to put a may be £10,000 model on a £20 jack or trolley ? Using a small single acting Hydraulic cylinder, manual pump and release with a restricter in it will work – but cost much more than £20 OR a double acting cylinder and change over valve and pump up and down !

PLAN B, Forget Hydraulics and use a mechanical system based on a leadscrew and nut – when your finger or leg is in the works it will hurt, this is a signal to STOP winding handle. Fail safe !!!! Noel.

If you could make a replica control valve, but with a tapered end, (Say 30 degrees angle ) so that the taper enters the hole when closed.

Unscrewing the valve will open up a small annular passage for the hydraulic oil, rather than the minute retraction needed to give the same rate of descent.

HTH

Otherwise, you just have to improve motor control skills!

I have the same control system on my Epco Trolley Jack, and Clark Engine Crane, but have never had a problem!

Howard