Posted 2011-04-12 2:55 PM (#132943) Subject: hydraulic jack - apparently it needed a break
Elite Veteran
Posts: 736 Location: Western WA
While unhitching my trailer this weekend at a show, I had to raise and lower my hydraulic jack a couple of times when I realized I needed a bigger block of wood under the foot. After a complete up/down cycle, then up again, my jack just stopped working. I was not yet unhooked from the truck and not yet plugged into shore power. My batteries were new last year and stored inside out of the cold this winter. Did I suck down my battery juice and they needed to charge up a bit before continuing? I gave it a few minutes and tried again and it worked just fine.
Posted 2011-04-12 3:04 PM (#132944 - in reply to #132943) Subject: RE: hydraulic jack - apparently it needed a break
Expert
Posts: 3802 Location: Rocky Mount N.C.
Hydraulic pump motor may have gotten warm shutting itself off to keep from overheating, or it may have tripped a relay/circuit breaker. Will your batteries recharge while being plugged up to your truck?
Posted 2011-04-12 8:08 PM (#132952 - in reply to #132943) Subject: RE: hydraulic jack - apparently it needed a break
Veteran
Posts: 264 Location: Sumas Washington
As your battery voltage goes down, the Amps to run the motor goes UP a lot, the more Amps you draw the more heat is generated. There is a thermostat device that shuts off the power when the motor gets hot. If you have to run your jack several times just start your truck to provide additional power to the electrical system. Charge your batteries and everything should be fine.
Posted 2011-04-12 10:47 PM (#132957 - in reply to #132943) Subject: RE: hydraulic jack - apparently it needed a break
Elite Veteran
Posts: 736 Location: Western WA
The truck was running at the time and the trailer was still plugged into the truck so I suspect the truck is not recharging the trailer batteries although I don't know for sure.
Posted 2011-04-13 12:47 AM (#132958 - in reply to #132943) Subject: RE: hydraulic jack - apparently it needed a break
Expert
Posts: 2955 Location: North Carolina
Retento is likely right. Many high current/torque motors have a thermal switch built into their windings. The purpose is to prevent motor burn-out. The motor is designed to run for only a short time. Engine starter motors are prime examples of the type.
If the problem was weak batteries, the motor might have run but the hydraulic valve would not have opened ( see past threads on hydro jack issues)
hydraulic jack - apparently it needed a break
