Ranco end dump question

How are they operated, hydolic- pneumatic-piston?

 

I’m not familiar with that particular breed of trailer, but ours has a spring-brake chamber on the tailgate locks and air cylinders on the high-lift arms for the gate. Same as a parking brake, the chambers on the tailgate locks are air to release, and you need air to lift the gate. If that trailer is the same you probably have an air leak somewhere. If the maxi chamber circuit leaks the springs will close the locks. The gate being lazy going up sounds like an air supply problem. A leak in one cylinder will usually make the gate lazy on one side only so it rises up crooked. Pretty easy to spot that.

 

I pulled a Ranco half-round about 20 years ago, and at one point I was driving down I-35 when my latches opened and my tailgate lifted all the way up. Good thing I was empty! The mechanic went through it and said there was an electrical short that had caused the malfunction, so that might be what you're dealing with.

 

Switch
Air can
Collapsed air line

is it trailer or is the truck not letting enough air over?

really not a hard system to go through

 

If they are air it can often be the valves are leaking or not flipping or perhaps there is a short in some of the wires.

I once found someone had nicked one of the control wires during the install and covered it with tape but as you can see below it finally corroded enough that the pilot valve wasn't get enough power to flip the piston reliably.

There are so many things it could be that really the only way to figure it out is to trouble shoot it with a multi meter etc...

This is especially true because it eventually works. Heck once I found that the exhaust port mufflers on the pneumatic cylinders were plugged, with would make the gate stick both down and up for a random amount of time.

Luckily the systems are quite simple if you take the time to understand them but intermittent issues always require lots of troubleshooting and remember to check voltages and consider adding pressure gauges as you troubleshoot.