A few more dump truck questions

Discussion in 'Questions From New Drivers' started by cmb7684, May 6, 2011.

  1. cmb7684

    cmb7684 Bobtail Member

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    Apr 26, 2011
    Metairie, LA
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    The handle on the raise.hold/lower is just a steel ball. There is no buttons and its stuck in the hold position. I have tried to wiggle it around and get it to unlock but it was a no go. I cant get it out of the Hold position.

    As far as the PTO. The fire trucks I drive are automatic. To engage the pump to pressure water we shift the lever for the PTO and put the automatic tranny in drive. This makes the pump operate. As you said you have to put the tranny back in neutral before taking the PTO out or you will tear things up and actually hear a grind.

    I will look and see if they have any other switched put it seems as though I should be able to put the PTO in the IN position put the truck in drive (if required) and then push the lever to Raise for it to start lifting the bed. So far I cant get the lever to come out of hold.

    As far as the lever as a spare for the tailgate lock. That sounds like something I may be able to fool with one day but looking under the truck it is no longer connected and there is nothing to connect it to so the guts for the manual lock must have been removed. Not sure why they would have done that but they did.
     
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  3. Pedigreed Bulldog

    Pedigreed Bulldog Road Train Member

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    That all looks pretty self explanatory...it's all labeled pretty clearly....tailgate...tarp...hoist. To get the PTO to engage, you'll pull up on that yellow part before it will move. If it locks one way but not the other, the way it locks will be off. If it locks to both sides or does not lock to either side, then you'll have to use your ears. One direction should send air pressure to the PTO to engage it, the other should exhaust that air from the line to allow the PTO to disengage. If you have a clutch in the truck, make sure the clutch is to the floor when you engage the PTO. If not, and the truck is fully automatic, you'll want the truck in gear and your foot on the brake to keep the truck stationary when you flip the switch to engage the PTO.
     
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  4. Pedigreed Bulldog

    Pedigreed Bulldog Road Train Member

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    One other thing on that...the lever to raise the hoist. Is it an air switch? It looks like it might be a mechanical linkage of some sort...perhaps a cable? Under the truck on the pump, there will be a solenoid of some sort...

    [​IMG]

    In that picture, it is the silver (aluminum) cylinder with the pair of air lines coming out of it....it uses air pressure to push the black rod you see between the hydraulic lines (it goes all of the way through) in and out, which controls what the pump is doing....holding, raising, or lowering. I've had those lock up...not hard at all to replace. If it is a mechanical linkage, make sure the cable isn't froze up. You might even try disconnecting the cable and trying to manually move the piston in the pump back and forth by hand.

    I would almost be willing to bet dollars to donuts that is where you'll find the problem....especially if it is a mechanical linkage.
     
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  5. cmb7684

    cmb7684 Bobtail Member

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    Apr 26, 2011
    Metairie, LA
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    Ok I can hear the PTO engage so I'm quite sure the PTO is working. The trouble seems to be isolated to the lever to raie/hold/lower itself. The lever has a steel ball at top and no button. It has a spring and a push rod going through the floor board. I will have to check and see where it goes from there but I assume it is either locked up frozen or locked up as a safety mechanism possibly due to low hydraulic fluid if that is even possible.

    I think my two challenges at this point are locating the Hydraulic fluid tank to make sure it has fluid (then checking into the leak/drip when I can) then checking into where that rod goes once it goes through the floor board under the truck.

    I will post some pics later.
     
  6. Pedigreed Bulldog

    Pedigreed Bulldog Road Train Member

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    I'm pretty sure that's going to be a mechanical linkage of some sort (most likely a cable) down to the hydraulic pump. The cable could be froze up, or the solenoid on the pump is locked up....but the cable would be the most likely culprit.

    You can (and I would recommend) buying an air solenoid for the pump and an air switch for the cab, otherwise that cable can potentially cause you problems down the road unless you keep it well lubed. I think the air switch I have (that does everything...PTO & hoist) was only $150 or so. The air solenoid another $50 give or take. Run some 1/4" air lines and you're good to go.

    The hydraulic tank might be tucked up inside the doghouse on the dump bed (by the hoist) between the back of the cab and the front of the dump body....easiest way to access it is to raise the bed a little.
     
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  7. cmb7684

    cmb7684 Bobtail Member

    29
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    Apr 26, 2011
    Metairie, LA
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    LOL not being smart butt at all but I had to kick back and laugh about you saying I might need to lift that bed a little to get to the hydraulic tank. I would give an extremity to see that bed lift a little right now lol. It did add a little humor to my day though so that is a plus.

    I did crawl under the truck and where the rod or shaft leaves the motor assembly and goes to the punp there is a wire on what appears to be a solenoig and it was crimped on. One of the wire coming from an end of the crimp connector is not there as if it pulled out. I will have to look again in the day light to see if it is there and try to snap a pic of it. My wife is emailing me pics of the upper linkage so I can post what I have so far. I will get them posted as soon as she sends. I will take some more pics of the underside when I can get some day light hours in.

    I'm not sure if the linkage I have is air activated yet or not. It seems mechanical but everything else has air lines. It was a public city truck and it seems they spared no expense at the time or maybe upgrading over the years.

    So far the gate locks are air activated, the axle diffrential lock and unlock is air activated, the PTO is air activated so the only thing I can tell so far that I'm unsure of is this lever. The pics may tell.
     
  8. cmb7684

    cmb7684 Bobtail Member

    29
    1
    Apr 26, 2011
    Metairie, LA
    0
    Ok here are a few pics taken of inside the casing of the PTO assembly with air lock controls for the gate and the infamous lever.

    As an added note I notice several fuses that are the barrel style stored in the door close grip. I winder if they had not had an issue with a fuse assembly and that plastic piece with two wires held in my hands in the pics I posted earlier may not be a part of a fuse holder and fuse that is missing? Anyine know if those two wires are supposed to make a loop and should have a fuse holder in them?
     
  9. cmb7684

    cmb7684 Bobtail Member

    29
    1
    Apr 26, 2011
    Metairie, LA
    0
    Here are more pics of the PTO and hydraulic system. Can the wire that is not connected be my trouble or is does that just do to the light in the truck for the PTO to tell you its engaged where the light is missing anyway.
     

    Attached Files:

  10. cmb7684

    cmb7684 Bobtail Member

    29
    1
    Apr 26, 2011
    Metairie, LA
    0
    And a few more
     

    Attached Files:

  11. SL3406

    SL3406 Medium Load Member

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    The wire is just for the indicator light. The pump is controlled by the cable attached to the lever with the ball on the end. My best guess is the cable is frozen up if you can't move that lever.
     
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