Lots of cred to Pistonskirt / Brian, whose press inspired mine. Brian, didn't you have a trick for flipping the pump lever mechanism 'round as well, or is my memory failing?
Thanks Rob, I did not pick up on your mention of "a yellow press" in your first post, it was a few years ago that I posted the details of my little press, over on the "other" forum if memory serves.
The lever mechanism modification is shown in my second pic, it is simply reversed on the clevis pin pivots (with suitable mods to the pivot rod) so that it strokes in the opposite direction.
In most cases all that is required internaly is to add a very light spring to the none return valve ball & (as you have shown) a suction pipe from the original oil inlet port.
A thought though... clutter bugs me. I like clean. I was thinking that maybe those external ram return springs could be moved, to maybe reside inside the jack housing. Hmm.
Another thought... The larger bottle jacks, twenty tonish sizes, take a long time to get anywhere when pumping manually. There oughta be a way to increase stroke without too much effort, like BillD just said.
Internal ram return springs are difficult to get right particularly if the ram has a decent length of stroke, it also makes assembly a real pain in the arse.
The larger (60 ton) press that I built had two stage pumps but that adds a lot of cost / complexity & was remotely mounted thus involving external pipework.
Although my present unit does not take much time to pump down & does not bother me for the relatively small amount of press work I do these days, I do have a 50 ton bottle jack which (if I ever find time
) will be similarly modified.
The solution I have in mind is to mount a double acting air cylinder where the pressure gauge fits on my present unit with the air cylinder shaft passing down through a suitably sized double lip seal in the base housing with its end screwed into the press ram. An extra none return port with ball & very light seating spring would be machined into the base plate which may require it's own suction pipe.
With a regulated low pressure air supply via a simple switching valve the pneumatic cylinder extends the press ram & displaces oil from the reservoir to the hydraulic cylinder via the additional none return valve, to retract the press ram the main return valve has merely to be opened in the normal way as the air cylinder switching valve is reversed.
Should work quite nicely & keeps the unit self contained apart from a couple of nylon pneumatic lines so that the unit can be easily moved sideways within the press frame as required.
That is all probably as clear as a bowl of oxtail soup....but I think that I know what I mean
regards
Brian