Cheap hydraulic rams and hand pumps

[Wazrus]

I have an Oriental hydraulic lift table, rated for around 400-pound lift. Recently, the thing refused to lift. It's one of those 'el cheapo' types. I have another, pretty much the same, and it's quite OK., and years older. So the idea is proven. The 400lb job is one of those integral hand pump/ram types, for which it seems to be impossible to source spare parts, at least not in Australia. I see long-stroke rams generally available, but no shorter types, which mine is.
I've replaced the balls in the ball valves, cleaned and bled the unit and replaced the fluid with fresh hydraulic oil.
You might say that the unit is cheap enough and why not simply buy another? Well, I've gone to considerable trouble to adapt the unit to travel over broken ground, towed behind a mower/tractor. I've replaced the original wheels with pneumatic wheels and casters of very good quality, so I'm keen to either fix the ram/pump or buy a new ram/pump. Replacing the whole shebang isn't an option.
On the bench, the ram will extend, but when set to work in the table, it won't start a lift at all. My thoughts include the ram seals, but there's no leakage onto the ram, other than a very thin oil film, which I'd expect. I can lift the table by hand, shut the bypass/control valve and the table will descend to about 2/3 of its full height and there it'll stay. I can sit on it, no problems and it'll stay up: overnight, if necessary. The fact that it'll stay up sort of rules out the rams seals, I think. There are no leaks from the pump or valves.
The ram is of a type often seen in trolley jacks, etc., but is quite a bit larger. Its operation is partly horizontal, changing to almost vertical as the table rises. To this end, the suction ball valve from the reservoir is spring-loaded, as might be expected.
Any thoughts from the membership?
Wazrus - Australia

 

[J_J]

I would suggest that the pump is not pumping, or the ram seals are leaking.

If you have a gage on the pump side, can you shut off flow to the ram and build up pressure?

If that is a SA cyl, is there is enough fluid in the pump to fill the cyl?

If you pump fluid into a good SA cyl, and shut off the return flow, the cyl should hold.

Have you bleed the cyl of air?

 

[wdchyd]

Pix..??

Sounds like a discharge valve problem......when you manually lift it and it stays, does to pump work....or maybe a teeter-totter motion?

How is it positioned in the frame (laying down? handle up?)....Pix please

 

[Wazrus]

To J-J and wdchyd
My apologies in not replying. I'm not very computer-savvy and I've just installed a new computer, which is quite different from the older one, so I'm back on the learning curve once again, where I've been since last December!
I eventually solved the hydraulic pump problem, with a visit to a distributor, where I was able to talk 'em out of the one and only spare they had and even that was from a damaged unit. They had another, which I bought also. Neither 'spare' quite fitted and there was a bit of head scratching to adapt one of the units to the table. Unit now operates in its assigned role.
To answer your questions: yes, it is a single-acting ram. There's no gauge. The cylinder and reservoir are integrated, as is the pump. Just like the ordinary hydraulic bottle jack.
I've attached some pix, which I hope fill the bill. Again, my apologies for the silence...

 

[J_J]

You might take another look at the ball and seat. If there is any rust on the ball or seat, you might not get a good seal.

 

[Wazrus]

J-J
I looked - I thought thoroughly - at the ball(s) and seatings and in fact, I replaced all the balls, with what I KNOW to be stainless balls. I also replaced the fluid. In the pix, the 'old' ram is shown leaning up against one of the trolley tyres. Maybe you might notice the difference between the rams: the 'new' one is shorter, having a shorter stroke, which needed me to fiddle with the geometry of the lift arms and also to fabricate a new pair of brackets for the ram support, at the side of the ram. The new ones are the galvanised pieces you might notice in the pix.
What bugged me, though, was the attitude of "just chuck it out and buy a new one", meaning a whole new trolley. All that was needed, at any stage, were the very simple seals or, failing those, a replacement ram. But it was all too hard. The throwaway society is alive and well.
Regards
Wazrus

 

[wdchyd]

J-J

What bugged me, though, was the attitude of "just chuck it out and buy a new one", meaning a whole new trolley. All that was needed, at any stage, were the very simple seals or, failing those, a replacement ram. But it was all too hard. The throwaway society is alive and well.
Regards
Wazrus

Welcome to my world

I started out in 1976 fixing garage jacks for another company.......in 1978 I hung out my own shingle, fast forward to 2014 and the only jack work that is seen is the occasional expensive porto-power pumps and rams.

the jack industry has changed to a disposable industry, if it wasn't for changing my strategy to do larger hydraulic components on commercial and industrial equipment I would have closed my doors years ago.......in the time and effort to rebuild one jack (hrs or most of the day sometimes) , I could make one hose in 15 mins and make the same profit without all the liability of a jack failing during warranty period

The foreign equipment manufacturers have copied the outside of hydraulic equipment but chinsed out the innards of the working jacks, it makes it very difficult to repair/rebuild something that was flawed in manufacturing from the get go.....the old stand-by jack brands such as Hein-werner, Walker, Blackhawk, Weaver, Ausco, Porter-ferguson have one by one gone out of business and most jack parts have become obsolete making repair work that much harder

In 1978 I bought a brand new Ford F150 for $5100 and 1 1/2 ton floor jacks (American made, commercial duty) were selling for just under $400......labor shop rates were well under $18-20 ........today that same truck is four times the cost( $20k )and the new jacks are one quarter the cost ($100)

You just try and make money fixing something like a jack (which are all made out of this country) and you will never make a profit unless you have a magic wand and don't mind fixing stuff with your endless free spare time

Sad but true......but then again, how many of us send out electronic stuff (tv, vcr's ect) to be repaired........today has become a throw-away society due to expensive cost of doing business and high labor rates