Hydraulics 101: Part 8, Switches
By Kevin Whipps
A switch has a very simple function: it switches power from one place to another. The switches that you use with hydraulics are three-position, momentary switches.
In the neutral position, power goes nowhere — let’s call that position 2, with 1 being up, and 3 being down on the switch. In the 3 position, power flows to the solenoid, which allows power to go to the pump. That turns the motor, creates pressure, and lifts the truck.
In the 1 position, power goes to the dump, and that releases any pressure in the system. The weight of the truck then pushes the fluid back in the opposite direction, through the dumps, into the return line, then the slow down, and finally into the tank.
Switches come in many different sizes, and usually in multiples of three. There are three-prong switches, six-prongs, and 12-prongs. I hear there are 9-prongs, but they’re hard as hell to find. Each prong refers to how many posts there are on the switch. In the example above, you’d be using a three-prong switch for one corner.
A three-prong switch is for something simple — turning on one pump and dumping one dump. These are usually used for individual switches, like a corner.
A six-prong switch is used for front, back, and sides. The switch turns on as many as two pumps and as many as two dumps. Remember that a six-prong has two pairs of 1’s, 2’s, and 3’s as per my example above.
Twelve-prong switches are for more complicated functions. Usually you use a 12-prong for a pancake switch, a see-saw, or something that requires a lot of moves. Pancake means all-up or all-down, and a see-saw lifts the front while dumping the back in one position, then in the other position reverses the process.
I know you’re waiting to hear what’s next, so here we go — tomorrow, Part 9, Suspension.
