Vermeer TM700 Trailed disc mower - hydraulic question

[lews]

I have a TM700 Vermeer which has two cylinders - right and left - for raising the mower. The left side isn't raising completely so I dismantled the cylinder worried that the nut on the rod might have come loose. It's fine though. But there's a scraper/seal? at the top that has a break in it (see photo). Not knowing much about hydraulics, I'm not sure if this is a scraper of some sort that is supposed to be split, or it's broken causing internal leakage. Could someone take a look?

Thanks, Lewis

 

[Tx Jim]

Welcome to TBN
IIRC if Vermeer TM700 hyd system is similar to TM800 the hyd cylinders are re-phasing cylinders so that operator must hold hyd control lever in raised position for an extended amount of time to allow cylinders to get equalized

 

[lews]

Really? Thanks for the info. The manual doesn’t say anything. I hate to put it back together without knowing about that seal thing. It doesn’t look right but it also seems odd that it lifts up , but just not to the top. Another question. The suspension system has these rubber pieces that cushions the “pivot” and they’re squeezed to death and dry rotted. Have you ever tried to replace? Without the hydraulic cylinder, the left side is sitting on the ground even at the lightest header setting.

 

[lews]

Really? Thanks for the info. The manual doesn’t say anything. I hate to put it back together without knowing about that seal thing. It doesn’t look right but it also seems odd that it lifts up , but just not to the top. Another question. The suspension system has these rubber pieces that cushions the “pivot” and they’re squeezed to death and dry rotted. Have you ever tried to replace? Without the hydraulic cylinder, the left side is sitting on the ground even at the lightest header setting.

Header flotation setting

 

[lews]

I put it back together and tried equalizing by holding down the hyd, but no change. It picks up the far side (cylinder) first and only when that side is at the top does the right side begin retracting (partially). I'm guessing it mean the added pressure in the system is causing it to work partially. IOW, that top seal is in fact broken and allowing pressure to bypass. When I crack the inlet nut, it's foamy fluid. It's so hard to get parts for Vermeer, but I've called the local dealer to work on it. I'd still appreciate anyone confirming the seal/scraper is bad so I don't wait for a kit for no reason.

 

[oldnslo]

Lewis,
in that picture is that piston and three seals all one piece or is the rod end gland tight against the piston. I suspect rod end gland is high against piston but would appreciate confirmation. If that is all the piston then I would suspect that split is just a glide ring for guidance and not a seal.

 

[lews]

It's all one piece. I spoke to the Vermeer dealer and he thought it was a scraper ring to protect cylinder wear. He says the right side is 2 1/4 in., with the left being 2 1/2. Although typically the fluid would flow from the larger (left) to the smaller, he says it works opposite and guesses that the other side (right) might be the problem, as fluid is not bypassing properly. Believe it or not, the kit for the small side is $69, and the large side is $169. Incredible. I'm going to detach both from the frame and see if they full extend and retract.

 

[oldnslo]

How are these two lift cylinders plumbed? Both cap ends teed together? If yes then typically with similar weight the larger diameter cylinder would move first.
Is it possible that there is some mechanical binding preventing one side from moving full range of travel?

is there a hose to the rod end or vented to atmosphere?

 

[lews]

I really need some help. I disconnected both sides and the left side still doesn't fully retract. It also extends further than the right side by the same distance it doesn't fully retract. When I tried to force it to a fully retracted position, it won't go. I followed the hoses looking for a crimp or something and found this valve just where the hoses start to go back to either side (see photo). If I remove the valve, I can manually retract the left side all the way in. The valve is spring loaded so I push on it and it moved inward as you'd expect. Is this valve simply a pressure release valve to dump fluid when it reaches a certain pressure? Perhaps it's unrelated to the cylinder issue and I'm just releasing pressure from the system. Maybe one of the hydraulic hoses has collapse internally and fluid is going thru under pressure but not able to flow backwards when it needs to release the pressure. Any help would be appreciated. I've got hay to mow.

Edit: Oldnslo, I missed your post as I was writing above. I need to see if I can follow the flow, but it looks like top of the left side (not fully retracting side) is connected to the top of the right side - but I'll go out and double check how it's plumbed. As you see above, there's no mechanical binding but somehow pressure isn't fully releasing from the top side to allow it to fully retract.

 

[lews]

Attached is the flow of the hydraulics. The top of the left cylinder (that won't retract fully) goes to that valve. As I mentioned, if I remove that valve, I can manually retract the cylinder so that means the hose hasn't internally failed, holding pressure. This is a straightforward spring loaded valve that is released when pressure reaches a certain level in the main line (large hose stated in diagram). The question is where the fluid is going. The valve sits in the return line to the tractor, coming from the top of the problem cylinder. But the pressure comes from the end of the valve - perpendicular to the hyd flow. It looks like that end sits in the main fluid line flow. So when the pressure gets high enough in the system, the valve opens and fluid from the top of the left cylinder escapes back to the tractor???? But if it's just a spring loaded valve, what's wrong? Why doesn't it work? There are rubber o-rings on the valve that don't look great but I can't believe that would be enough to cause it not to work. I don't know.