1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

MVP Right wing movement when raising

Discussion in 'Truck & Equipment Repair' started by tws0570, Nov 29, 2015.

  1. tws0570

    tws0570 Junior Member
    Messages: 4

    Hey guys, new here, not new to plowing. Just bought a Unimount MVP 8.5, its in pretty good shape despite its age, everything works but I'm having this issue which I'm not sure its an issue or if that's the way it was designed. When I raise the plow, the right wing moves back a bit, and it does it every time I raise. If its in Vee, it wont do it obviously because of the stop, but if its not at the stop it will move back an inch or so. Almost looks like it loses pressure to hold the cylinder. I tried looking though the mechanics guide but not a whole lot could be found. Could it be a stuck valve or does everyone have this? Thanks
     
  2. Philbilly2

    Philbilly2 2000 Club Member
    Messages: 2,586

    Welcome to the site.

    I would start by checking and replacing the Pilot Operated Check Valves.

    It has been a LONG time since I have worked on a unimount pump, but I believe that it is either the A or B check that are used on right retract. Sounds like it is bleeding over to the secondary.
     
  3. Philbilly2

    Philbilly2 2000 Club Member
    Messages: 2,586

    I just did a search.

    Up in the left hand corner, search Unimount MVP and there are tons of threads on this issue.

    Check those out and I think you will find your problem.
     
  4. tws0570

    tws0570 Junior Member
    Messages: 4

    I read a few threads as you advised, I'm just going to order new PO valves. I took the old ones out and didn't notice anything wrong with the o-rings but given it seems like the problem that everyone is having with the same symptoms, I'm going to say its a fairly good assumption. I'll let you guys know if it works.
     
  5. tws0570

    tws0570 Junior Member
    Messages: 4

    Looking over this mechanics manual again, I believe I may have solved my problem. Apparently the plow was designed for a smooth operation controller which means the spools stay open a split second longer than the pump running, which I would assume is to relieve the pressure. I have a custom controller which was built for a straight blade which does not use this smooth operation. Anyways to test my theory I used a small capacitor in parallel with S2 and the magically retracting right wing disappeared. I'm not sure if this is the way it works, but it works haha. Either way I'll replace the PO valve when it comes tomorrow but starting to wonder if it was even bad.
     
    Last edited: Dec 1, 2015
  6. tws0570

    tws0570 Junior Member
    Messages: 4

    And also with any function aside from dropping.. the pump runs, if the spools deactivate before the pump pressure goes down, the ring wing retracts because nothing needs to be activated besides the pump for the right wing.