Looking for Help Wiring Bottom Dump Controls

there are a couple different styles. one you need a hot charge wire, a ground and then a open hot and a close hot. when the circuit collapses on the charge wire on it goes into full close.

then there is the style that looks more like what you have where its basicly a spool valve that detentes to closed. basicly you charge the solinoid it should move the spool valve and gates should open collapse the circuit and they should close.

trailer i have has a valve that looks very similar but it has manual hand valve on it as well. you can ground to chassis and then run a hot to the solenoid.

i would wire your switches so you have a 3rd kill switch. power feed into one switch wire in series to your actually dump switches. your dump switch for each gate can be wired in parallel after the switch in series from your power source what this will do is make it so two switches have to be thrown for the gate to open. so if you accidentally bump one switch rolling down the road you don't drop your load on the highway.

 

looks like you are on the right track. your have to excuse my crude ms paint drawing here but here is a 3 switch and 4 switch circuit and in red is a optional led light to remind you to shut your road switch off after you close your gates. i did this on my first truck i didn't do it on my current truck, and i kinda wish i had, i every time i use my belly dump i remember id like to ad one then i park the belly dump and forget about it.

i use the round 6 pin automotive trailer light connector for my belly dump. looks like what you have there, i run some controls on other trailers threw the same plug otherwise a 4 pin is fine for a belly dump as well. i only have 1 gate and i also have a ground wire that runs threw the plug as well that grounds right next to the valve. witch is probably completely unnecessary as your trailer lights run a ground wire to chassis as well. plus a a poor ground threw the 5th wheel.

 

another thing is sometimes the valves can get a little sticky esp in cold weather it does not look like you have oilier installed on the line feeding from the tank to the valve. it would not be a bad idea to add one. otherwise your need to pull the air supply line and spray some wd40 or similar in it from time to time. a little oil is good for the seals in your gate cyl's as well.

the style valves you have seem to me to be far less finicky than the style on the newer trailers though.

 

if your talking about the gratech auction, all there truck stuff was pretty well run threw the ringer. there heavy haulers were pretty good and went cheap too but all there belly dumps and esp the side dumps there are only a couple of them that were worth much more than scrap.

 

yup nov 7th richie brothers auction was the gratech retirement auction. Lot # 465
1972 FRUEHAUF 38 Ft T/A Bottom Dump Trailer
Details: spring susp, clam gate. More details
MINOT, ND
Tuesday Nov 7, 2017
Sold for: USD

i have contracted for them a lot over the years i had never seen that trailer. i would guess its been sitting for a very long time. probably a good thing they have not really maintained there truck fleet very well for the last several years.