Front Electic Jack Problem

[filecutter]

My front electric jack keeps blowing fuses any suggestions as to why. 2012 Larado with no apprent shorts or wiring problems. thanks in advance.

[therink]

Are you extending or retracting it to its full limit of travel? I have read that this put excess strain o the motor causing overload and blown fuses. I make sure to only raise the legs as high as needed for safe towing but never all the way up.

[BruLaz]

Tongue weight too heavy for the particular model of electric jack?
How old is it? If older, maybe just needs some gear cleaning/lube?
If trailer's still under warranty, get them to put in a heavier-duty one.

[kimanderson98642]

I also learned the hard way. Not to raise or lower it till it stops. it will blow the fuse every time. Mark or paint a line on it to help stop short of its max and no more problem. You could also put a auto reset circuit breaker in place of fuses.

[JRTJH]

Installing circuit breakers to replace the fuse is OK, but it is not a good idea to continue to raise or lower the landing gear to it's limits. Putting in a CB will stop the fuse replacement hassle, but will do nothing to protect the gears from being jammed. There is no electrical stop for the motor, so every time you run it all the way up or all the way down, the gears bind, overload the motor and blow the fuse. That overload (blowing the fuse) is what removes electrical power and protects the motorand gears. If you put a slow blow CB in the line, you'll put more torque on the gears before the motor stops. Essentially, what you'll be doing is allowing more grinding and torque to the gearbox before the system shuts down. Whether you use fuses or circuit breakers, sooner or later, you will damage the gearbox and once that's done, the only thing you can do is either rebuild it or replace it. If the damage happens at home while unhitching, at least you're not stranded, but if it happens at a remote campground, you're in for a heck of a time trying to hitch and get home. No matter where it happens, it's going to lead to a lost camping trip, lots of hassles and expense. All of that can be avoided, for the most part, by simply not running the gear to the top or bottom limits. Using tape, paint, magic marker, whatever you choose, to mark the gear about 1" or so from the extreme top and bottom, and then watching not to go past the marks will prevent damage to the gearbox and save you money.

[michol02]

I had the same problem. Blew fuses all the time. I greased the shaft and gears and it did ok for a short time, then just burned up one day. I think my tongue weight was too heavy. I replaced it with a Brute Force 4000lb and have never blown a fuse since. It automatically cuts off when you get to the end of it's limits. Found it on Amazon.

[gkainz]

Mine will blow if I start/stop/start quickly (like if my finger slips off the switch)?

[AzDesertRhino]

We just moved up to a 5th wheel and the first lesson I learned was when I over retracted the landing gear.

Blew the fuse and then had to trace the wiring to find the in line 30 amp fuse.

Lesson learned, wll not do that again.

[Festus2]

An RV repairman recently suggested to me that I use a 40A fuse instead of a 30A. According to him, the high speed gear box or motor (can't remember which) could better handle a 40A fuse without causing any damage to the motor. He said that he installed a 40A fuse in a couple of RV's that he owned without any further problems of blowing fuses or other damage.

I'm rather skeptical of his advice since I would think that this system is designed for 30A and that there would be some danger in installing a higher-rated fuse.

Comments??

[JRTJH]

There is a guideline for the size of wiring based on amps carried and distance. According to that chart, 10ga wire can carry 30 amps for 9 ft.
The first 40 amp rating is for 6ga wire for 17 ft.

The chart is here: http://www-ppd.fnal.gov/eedoffice-w/...olt_System.pdf

Granted, it is based on voltage drop, not heat buildup (insulation meltdown) but losing voltage creates increased drag and damage to the motor, so, I'd think following this chart would indicate NO to installing a 40 amp fuse in 10 ga wire for any distance.

I think the biggest concern I would have is how much torque will the bigger fuse allow in the gearbox before the bigger fuse breaks the circuit to protect the mechanical lift system? Sure, a 40 Amp fuse may not blow before the motor reaches its maximum torque and stops turning, but repeatedly stressing the gearbox by putting that much "extra" torque on it to actually stop the motor without blowing the fuse puts a direct short on the motor armature until you lift your finger from the switch. With the 30 Amp fuse when it blows, the "system" removes power from the motor before the armature stops turning and shorts itself out. This may be oversimplified, but hopefully it explains why a bigger fuse may not blow, but can still cause significant damage to the motor and/or gearbox.

I maintain that the best way to protect the system is simply not to hold the switch and allow the gearbox to travel to the upper or lower limit. Doing that will protect the gears and the motor, neither of which have a self limiting switch or stop (other than that 30 amp fuse),

[cathcartww]

Make sure you have a good ground. A bad connection can reduce the voltage under load conditions which increases the amps being pulled. Most of these are only grounded through the mounting bolts. On our last trailer, I had to run a separate ground wire directly from the jack to the battery to get it to run reliably.

[SlowPoke]

Originally Posted by michol02

I had the same problem. Blew fuses all the time. I greased the shaft and gears and it did ok for a short time, then just burned up one day. I think my tongue weight was too heavy. I replaced it with a Brute Force 4000lb and have never blown a fuse since. It automatically cuts off when you get to the end of it's limits. Found it on Amazon.

I too have the Brute Force, and run it to it's limits up and down. The instructions say it has an auto stop feature built in that will NOT allow it to travel too far in either direction. I love mine!

[Ron]

If you go to the search box and type in (245RL Blowing Landing Gear Fuse) you will see my post of the 30amp circuit breaker I installed in our last Couger we owned................