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My dump truck will not dump heavy loads. Why?

Discussion in 'Truck & Equipment Repair' started by elite1msmith, Jan 27, 2011.

  1. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    2001 f 550 7.3. Pto pump dump. Has a sissor hoist for an 11 foot dump bed. Last week we scaled in at 4,000 in the bed pretty much equally distributed and the hoist would not raise the bed. It would dump 3500 lbs, but not 4. This is a problem since this truck is rated to handle 7,000 plus in the bed. When empty the bed flies up no problem, almost too fast. I don't have much knoweleg about this style, so is there a pressure adjustment, or is the pump not geared correctly?like it's too fast and not enough torque? Little help please
     
  2. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    there should be a pressure adjustment at the pump. depends on the type of system. shoot me a pic of the pump and valve assy and we will what system you have.
     
  3. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    Intertech g101 pump, I will have to look at the valve but I believe it's bolted right to the pump
     
  4. LON

    LON Senior Member
    Messages: 749

    G101 is probably only rated for 2000psi. Your scissor hoist is going to require 3000psi to lift. Load to heavy towards the front of the bed & it's not gonna lift. This is why front telescopic hoists are so much better.
    7000# rated? What does it weigh empty?
     
  5. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    the valve should not be on the pump. is the valve electric or cable control? the valve should be adjacent to the hyd tank.
     
  6. LON

    LON Senior Member
    Messages: 749

    G101 is a dump pump w/ spool valve incorporated into the casting. Can be either a 2-line or 3-line system depending on how it was set up. Pressure relief valve is between the suction & pressure ports.
     
  7. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    Cable. I want to say I remember something about it having a 1.5 gear? Truck with plow and salter scales in empty at 10,800 lbs. Sticker on the door says I'm good till 17,500. And we all know I don't mind going above that a little

    How would I mow what the scissor is rated for? Would there be a spec on the cylinders?
     
  8. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    see if there is a brand name on it and a serial number tag. also look on the body.
     
  9. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    I assume then after finding out what the max psi the hoist cylinders will handle, I disconnect the hose to the cylinder, install a pressure gauge and adjust from there huh?
     
  10. LON

    LON Senior Member
    Messages: 749

  11. meadowstruck

    meadowstruck Junior Member
    Messages: 5

    Did you just put this pto/pump/hoist combination? Or has it been working well untill just recently?

    If it is a new combo/install, then you must have the hoist make/model/specs to verify the required operating pressure.

    If it is an existing setup that WAS working fine, then most likely the pump is worn and failing. The only sure fire way to test it is with a specialty tool called a hydraulic flowmeter. Most hydraulic and/or truck equipment shops can do this in 45-60 minutes.

    The G101 is typically rated for contractor box dumps with headmount (meaning right behind the cab) telescopic cylinders. Scissors hoists normally require more pressure than that pump will generate.

    And the 1.5 should designate a 1.5 inch gear width on the pump which dictates how fast the system is.
     
  12. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    Bought the truck used so I have no idea, just very disappointing
     
  13. the new boss 92

    the new boss 92 2000 Club Member
    Messages: 2,989

    any hydro leaks? im no expert but thats were i would start, also look for wet or damp seal's. fluid could be getting bypassed some how and not going were it needs to be.