About Us
Welding & Hardware
Hose & Hydraulics
Items in Stock
News & Events
Your Troubleshooting Questions Answered
Contact Us








Troubleshooting Article Archive:  July 2007          
Trouble- shooting New Equipment: Auto- Loader Hydraulic Valve Bodies
As the owner of an equipment repair shop, I can divide my customers into two camps:  Those who do trade-ins every year so they only operate new equipment, and those whose business strategy includes the operation of older, used equipment.  It seems to be an article of faith among the new equipment devotees that new equipment won't break down.  In fact, though, new equipment does break down, often before you've even put it in service.  Moreover, new equipment has some troubleshooting challenges of its very own, challenges you never see on old, used equipment.

The most common new-equipment breakdown I see is sticking spools on the hydraulic valve body of auto-loading trucks.  The spools in such valve bodies, which are moved in and out by electromagnetic coils, are made with a precisely machined steel outer diameter to fit in a precisely machined metal bore in the valve section.

The physical contact between the spool and the bore is metal on metal -- there is no rubber or plastic between the two.  When the parts are new, the fit between the two is very close.  Sometimes the fit is so close that the spool will get stuck in one position and the electric coil that moves it isn't strong enough to dislodge it.  Older equipment with many hours of motion and use in the spools rarely has this problem because repeated use has made the tight fit a little less tight.  When the spool gets stuck, the wrecker boom will fail to move when you press the button on your remote control.

Solve this problem by using the manual override feature which comes on many, but not all, auto-loading truck valve bodies.  The manual override requires you to use two hands simultaneously.  With the engine running, use one hand to move the spool by pressing in on the round knob on the end of one of the valve sections (see photo).  At the same time, with your other hand, depress one of the buttons on your remote control.

You have to perform both actions at the same time in order for the manual override to work.  The wrecker boom will start moving again.  If it's moving in the wrong direction, keep pressing a button on your remote control and with your other hand simply press the manual override knob on the opposite end of the same valve section.  You have to use the strength of your whole hand and press hard on manual override knobs to get them to operate -- gentle fingertip pressure will not do the job -- and I usually use my thumb to maximize the force.

Stay tuned:  More troubleshooting on brand new equipment in my next column.