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17" Cinci Hydrashift changes speeds unexpectedly

wfissell

New member
Hi, All,

thank you in advance. I am a relative noob getting accustomed to a 17 cinci hydrashift, purchased "ran when parked". After a bit of cleaning, rinsing, fresh fluids, degunking the QCGB and making sure the oilers work, I'm pretty pleased overall. Its being powered by an ARP three phase. The major problem with it is some bed wear form abuse, but I bought it to surface flywheels so that doesnt affect me and probably wouldnt seriously affect anything.

It shifts very nicely and the clutches seem OK- it does tend to set the chuck spinning gently when you power on the motor, but a tap of the brakes stops it immediately. It's very challenging to get the the QCGB to pin to register into the selected gear.

I do notice that at speeds above about 540 or so, the lathe will spin up, and then after 30 sec to a minute speed up a second time to a higher rev. I do not have a tach but could probably obtain one. This is not a shifting issue- its a motor speed issue. Any hints?

thank you!

Bill
 

Elwood1968

Member
By "motor speed issue," do you mean that you can observe or hear that the motor is changing speeds after 30 seconds?

What motor is on this lathe? If it's the original three phase motor, is it a single speed or two speed (i.e. the windings are done such that it can be operated at two different speeds depending on the control relays in the box mounted on the backside of the headstock)?

A photo of the data plate on the motor, and a description of which ARP (American Rotary?) phase converter that you're using might be helpful, too.

The spinning spindle seems typical of these Hydrashifts; mine does the same thing. Probably a slight drag in the multi-disc clutch, but if it stops with the brake, then it's nothing I'd be too concerned about.
 

wfissell

New member
Thank you for the very quick reply. RPC is an ARP AD-10STK - none of the other tools in the shop seem to have power fluctuation problems. I didnt state, but should have, that the change in speed occurs over 10 or so seconds, and definitely seems to transition from one specific value to another. Its not hunting. Ill take a pic of the motor plate- AFAIK standard 3ph that came with it, has 240 and 480 wiring options but I didnt see anything to suggest two-speed wiring.
 

Dan from Oakland

Active member
I suspect the clutches as well. Don't let them slip- adjust them. Its pretty easy.
Pull the top cover off the headstock and they are right there. Each clutch has a small wire clip that you release to turn the adjustment. It does not take much to tighten them up. This is all explained in the user manual-above. If ya burn up the clutch plates, they are not easy to get AFAIK.
 

Elwood1968

Member
If it didn't do it before and does it now after cleaning. I suspect the twin disc clutches are worn and when it is engaged they slip and it turns. Or the hydraulic pressure is to low. I found this and will keep looking. http://vintagemachinery.org/pubs/177/25774.pdf

Clutch slippage would seem like the likely culprit, but the OP observed that the motor transitions from one speed to another speed over a period of ten seconds. I read from that post that the two speeds are steady state, one before the transition, the other after. If the clutch is slipping, that pattern seems like an unlikely result.

Low hydraulic pressure will result in difficult or missed shifts. It's possible that the hydraulic pressure is causing a delayed shift, but (a) that isn't what was described, and (b) when my Hydrashift has suffered from low pressure, the delayed shift was accompanied by cringe-worthy gear crashing noises since the spindle was already in motion when the shift pistons finally starting pushing the sliding gears on the shafts.

I'd be inclined to start looking on the electrical side before the mechanical side of things.
 

wfissell

New member
Hi,

thank you for thinking about this. Richard, especially, thank you for taking time to think and reply. It could be clutches and I have no idea if it did it 'before' as I drained it rinsed it and refilled it with the specified oil before I ever applied power.

I did test it with some heavy (for me) cuts in mystery steel and I could certainly hear the motor sound change with the load and I was unable to stall it. Could still be clutches for sure- Im not someone who takes huge joy in trying to push the machine as hard as it can.

Heres the motor plate.
IMG_20211129_200228706.jpgIMG_20211129_200228706.jpg

IMG_20211129_200228706.jpg
 

wfissell

New member
Oil sight glass, clutch adjustment

Hi,

wanted to bump this back up.

I see in the manual instructions on adjusting the clutch but the instructions just say 'suitable'. Right now the clutch does seem tight enough that it will spin up when the motor comes on, but, then again, its a tired beast and maybe it does need clutch pack tightened.

I need to clean the oil sight glass. I cant see oil flowing and I suspect its overfull. Theres plenty of oil pouring out of all the right places and it shifts smartly.

My pressure gages are 1/4 NPT, not the thread thats in the pressure port. Can anyone point em to an adapter?

Still got speed up/slow down probs.

thanks in advance.
 

Elwood1968

Member
If you try adjusting the clutch, be careful. Replacement parts for these Rockford Pullmore clutches are almost impossible to find. I have a PDF of the Rockford factory manual on disassembly and adjustment of these clutches if that might be of help.

As to the oil sight glass in the headstock, it's possible that the copper feed tube into the top opening on the backside of the sight glass has become dislodged, and instead of feeding oil into the sight glass, it's just dumping into the headstock sump. Easy enough to fix once you get the heavy cover off of the headstock. Or perhaps that tube is plugged or pinched. If you can't get the sight glass clean, replacements can be found. I think it's a 1-1/2" diameter, the same as is used on Hobart commercial kitchen mixers. Or just buy one from Bullseye Industrial: 1-1/2" OD Press In Style Liquid Level Sight Glass Bezel NOS | eBay

I don't recall now what size the port is on the shift block inside the headstock to tap in the gage, but if 1/4" NPT is too large, it's probably 1/8" NPT.

As for the speed problem, have you tried taking any heavy cuts on this lathe? Does loading up the tool pressure have any effect on the spindle speed?
 

wfissell

New member
Thank you for the input. I did find a slipping belt on the hydraulic pump so Ill report back after leaning on it hard this weekend. I did get a sense that yes, I could load it down and it would slow, but other times it cruised along just fine.
 

Elwood1968

Member
A loose belt to the hydraulic pump should only affect the hydraulic system pressure, i.e. the shifting function and lubrication. Spindle drive is entirely mechanical, although the belts from the motor pulley to the clutch input shaft could also be loose?
 

wfissell

New member
I dont think they were slipping- it was the belt to the hyds pump that deteriorated. Ill check hyds pressure when I get an 1/8 NPT adapter.

The instructions say to lift the clip a tiny bit and turn the clutch by hand, but it does not say at all how much is too much or too little. Suggestions?
 
Suggestions?
Just one ... whatever you do, don't get the bright idea to turn the thing on with the headstock cover off "just to see what's going on." You won't see anything ... for about a week, while you wash the oil off your face, the ceiling, the floor, anything within a five foot radius of the lathe.
 

Elwood1968

Member
I dont think they were slipping- it was the belt to the hyds pump that deteriorated. Ill check hyds pressure when I get an 1/8 NPT adapter.

The instructions say to lift the clip a tiny bit and turn the clutch by hand, but it does not say at all how much is too much or too little. Suggestions?

Less is better. I'd start with one notch and see how much, if any, it changes things. If you put too much tension and break that spring, you'll be hard pressed to find a replacement. At worst, you could cannibalize the brake side of the clutch assembly, but then you won't have a brake function.
 

Elwood1968

Member
Just one ... whatever you do, don't get the bright idea to turn the thing on with the headstock cover off "just to see what's going on." You won't see anything ... for about a week, while you wash the oil off your face, the ceiling, the floor, anything within a five foot radius of the lathe.

Cincinnati used the relief port of the hydraulic valve block to spray lubricate the clutch assembly, but it's more like a garden hose than a laser. Whenever I have the headstock cover removed, I add a short length of bent copper tube (see red arrow in photo below) to the relief port elbow to direct the output back down into the headstock.

100_0813.jpg
 
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