Hydraulic mill has started lurching and jerking through the log...

[oklalogdog]

My hydraulic mill has started lurching and jerking through the log even with new blade and on a small green 12" cedar log. I've tried everything I know and seems nothing helps.  It also stops several times during a cut and I have to increase the flow then it starts with a jerk. I thought maybe the drive chain had slipped a link and the head was running crooked but that didn't seem to be it.  I'm pretty much at my wits end.  Has anyone had any experience with this or have any ideas?  Would appreciate some help.

[oklalogdog]

One thing I'm wondering is I changed over to a thinner hydrualic oil last winter and have not changed back to the thicker yet.  Could this possibly cause all this jerking when the oil gets hot and thin?

[ladylake]

  Check the rollers that  the head rolls on, they need to be greased every day.  Steve

[oklalogdog]

OK - will do.

[ozarkgem]

check your oil level and filter. Could be just letting enough oil through to cause problems. It may not be getting a steady supply.

[oklalogdog]

I have checked oil level but not the filter.  It does have a gauge however that shows the filter to be OK. One other thing - it seems to go OK when I first start in the morning but as it warms up I start having my problems.

[TimGA]

  I am with Steve, check your carriage rollers. Look at your left front roller going to have to lift carriage up. The hyd drive motor will look like it is jerking, I will bet it runs smooth in reverse. Pm me if you want to talk about it have done this a couple times.   
                                                        Tim

[oklalogdog]

I have sent you a PM Tim - thanks.

[Solomon]

Could be a number of things, check the simple things first.
Check for water in your system,  if your fluid is not contaminated,
Change your filters, filters are cheap.
Check to see if you have a pice of trash or sawdust in the valve that cotrolls your feed.
Check with the manufacturer and see that you are using the right fluid.
Check for air trapped in the feed motor.
Also check to see if that valve is  opening like it should.
If all that checks out and you've serviced your mill, then start looking for a more serious problem. like a crack in the body of that valve or a pump going bad.   
I would put a new belt on the pump with some belt dressing and make sure it is as tight as it is supposed to be as a simple check as well.
The fact that it seems to run alright when it's cold, tells me that it is very likely a simple and inexpensive problem to fix.
  I'm am sure there's more simple things that the other good folks on here can point out that I've missed.
  Remember, you're human , we all miss simple things,  don't let it get you frustrated.

     Pete,   Chesapeake , Virginia

[Will_Johnson]

Most likely this would result from a loose or partly loose sprocket on the drive shaft at the top of the carriage.

Certainly something to check.

[pine]

One thing I'm wondering is I changed over to a thinner hydrualic oil last winter and have not changed back to the thicker yet.  Could this possibly cause all this jerking when the oil gets hot and thin?

Not knowing what year mill you have but the recommended weight hydraulic fluid for many years has been AW46 anything else would go against the manufacturer's recommendation.  I certainly would not go lighter weight at any time. 

Ladylake's suggestion is a great place to start.  Also look for a debris buildup on the frame around the chain area as that can cause issues as well.

Look at the drive sprocket and make certain that the key is not missing.

Call Jason he is good on this stuff.

[oklalogdog]

Pine - it was actually the manufacturer that told me to go with the lighter weight oil and told me the weight to get.

[oklalogdog]

OK folks - thanks so much for your comments and help. It turned out to be a combination of things as a lot of things are. I have found out in this life that most problems are not just black and white.  It was in fact a carriage roller bearing like Steve and Tim said but not the grease-able ones on top but one of the small bearings underneath.  It was frozen completely up and had been dragging and hanging.

Fixed that problem but then the mill continued to stop at certain points through the log. So, I took the chains loose and the right side chain was fine just like new but the left side chain that catches all the sawdust, water lube, and gunk had numerous frozen links.  I soaked the chain in diesel over night then worked the links by hand and it seemed to free them up.  I tested it out late this evening and everything seemed to be working smoothly.  Hope so - got a big sawing job tomorrow.

Later Taters - and thanks again.  Oh yeah and I'm still going back to the thicker oil and will change the filter.

[oklalogdog]

Good idea on the sprockets I will check them too.  One thing is for sure - after tomorrow I will know if I have corrected the problem.