Barber Chairs Won't Stay Up

If the oil is not leaking externally (say onto the floor), there may be yet another piston seal inside the cylinder. I don't know about your chairs, but piston seals are often a set of stacked chevrons.

thanks for help- there's no fluid on the floor. I'm not sure what a chevron is, are they metal?

They are basically a V shape in a stack of 3 or 4, made of Teflon or a similar material. The oil pressure tends to push them into good contact with the cylinder wall. The top and bottom of the stack are squared off, and the whole business comes typically as a set.

I don't know if you've seen this place, but new pumps seem pretty reasonable.

http://www.kellerinternational.com/c-19-Parts-and-Pumps.aspx?pagenum=all

You could have a chat here. One of them might know something of help.

I've heard that some aging hydraulic systems are helped by using the additive sildenafil citrate to improve hydraulic pressure.

_{Never needed it myself.}

If you "hang around" long enough, you will.

If you find the answer please let me know. A hydraulic bar stool dropped me this afternoon!

In a general single action jacking hydraulics view - never having played with a barbers chair;

If there is no oil on the floor - i.e. coming out of the rod bush, the piston seals are not leaking.

So;

Suspects are; (in detectability order)

The pump valves are leaking.

If so, it will generally manifest in the pump lever rising. If that is the case, fix that seal set first.

The lowering valve is not seating.

First make sure it actually seats with the available peddle? movement. I.e. it may need more rotation to seal than the linkage stops allow.

If it is physically seating, but still leaks, it needs pulling down and lapping of the spindle and seat.

The over pressure valve, if it has one, is leaking.

They are usually a ball and spring. It could be a tired spring, or some gunk, or a corroded ball or seat. Fixing these physically is fairly simple but you need to know what pressure it is meant to relive at, and obviously a gauge, and generally some patience with shim combinations and measuring thereof.

Notes;

It's a good idea to photograph everything and mark things to facilitate reassembly. And watch out for balls and springs and shims.

Hair is possibly the worst enemy of hydraulic valves. And that's just in 'normal assembly conditions'.

It may be a single hair per chair causing this.

I am having the same problem. Have you ever figured it out?