Clausing 5914 speed control not holding

[SteveM]

On my dad's Clausing 5914, with the hydraulic variable speed drive, If you have the speed anything less than about 1,300, the control will drift lower all by itself. At higher speeds, it will hold.

I have heard that I might need to bleed the system, but before I go doing anything, is there anything else that might cause this and what do I need to do to fix it?

Steve

[wlw-19958]

Hi There,

Most likely, it is air in the hydraulic system. I have overhauled many
of these (the 6900 series use the same hydraulics as the 5900 series
lathes as well as the 8540 series mills. The 1300, 1400 and 1500 series
lathes also use the same master cylinder and their save cylinders use
the same piston seals).

There are two different types of master cylinders and two different
types of slave cylinders. I have called them "Old Style" and "New Style"
to differentiate the two types. The "Old Style" cylinders are made from
heavy walled steel tubing and the "New Style" are made from rectangular
blocks of Aluminum. The "Old Style" are no longer supported by Clausing
(but I have seals for them if your father needs them).

The hydraulic bleeding instructions are in the manual. The "Old Style"
instructions are different than the instructions for "New Style" so make sure
your father has the proper instructions for his style cylinders. I have run into
some that will not successfully bleed using these instructions. I contacted
Clausing and received an "alternate" set of instructions for bleeding the
hydraulic system. Sometimes, the air has difficulty "bubbling-up" through
the hydraulic hose (depending on the viscosity of your hydraulic fluid).

It is possible that the counter balance spring for the master cylinder
does not have the correct pre-load but this isn't that common. This
spring is under the speed control handle and dial. A weak spring usually
causes the control to drift down at the higher speeds and not just the
lower speeds.

Anyway, the place to start is bleed the air out of the system. If it still
creeps down after he is sure the air is out of the system, check the
balance spring, but it is very difficult to make sure all of the air is out.

In case you need them, here are the "alternate" bleeding instructions:

Bleeding Hydraulic System


BE VERY CAREFUL WHEN BLEEDING THE SYSTEM AROUND MOVING PARTS.


This procedure will work much easier with 2 people:


1. Fill upper cylinder with oil

2. Start lathe; crack hydraulic hose at lower pulley cylinder.

3. With the lathe running, slowly turn to high speed, just before reaching high speed, close hydraulic hose on lower pulley cylinder. Turn to low speed.

4. Stop the lathe and start at # 1 again.

5. You may need to repeat this process a dozen times before all of the air is bled from the system.

Let me know how it goes. Good Luck!
-Blue Chips-
Webb

[teachingscience]

Hey wlw,
I just got a clausing 8540 mill which has that same hydraulic speed control. Do you still have the seals for the old style cylinders? Mine leaks so I assume it needs rebuilding. I haven't taken it apart yet but it leaks very badly and coated the belts with oil with less than two minutes of running. Any information you can give would be greatly appreciated.


Charlie

[SteveM]

I believe that my dad got the seals from Clausing.

Not the cheapest place to get them, but they would be the correct ones.

Once you rebuild it, if you are not using it for industrial use, it will probably last the rest of your life.

Steve

[Harold_V]

Hey wlw,

wlw hasn't visited this venue for more than a year.

It's likely that a visit to a hydraulic shop could result in obtaining seals that will serve your needs. Worth a try.

H

[LIALLEGHENY]

Hercules Sealing products in Florida would be my go to for the seals. Herculesus.com

Nyle