A check valve is like the valves in your own heart. The check valve just like your heart valve keeps fluid moving in only one direction. Most kits for beginners come with 3/8th check valves but as you may have noticed hoppers and dancers use 1/2 inch, 3/4 inch and even one inch check valves. The larger check valves allow for more flow in the system and have less restrictions. With a larger check valve you are also less likely to blow a pump head out.
A slowdown valve is used to control the flow of hydraulic fluid returning to the hydraulic reservoir. Most slowdown valves are plumbed in after the dump but on hoppers using Adex or Adel dumps a slowdown may be used before the dump to protect the dump from pressure spikes and increase accuracy. Slowdown valves come in many sizes from 1/4 inch to monster zig zag aircraft slowdowns. Most kits come with 3/8th slowdown valves to start out with. Cheap slowdown valves tend to have a problem with leaking around the handle shaft.
Check Valve Pictures
Above: Here is a male 3/8th check valve that typically comes with most hydraulic kits. These usually work good as long as you keep the oil clean from debris.
Above: This check valve was determined as bad. When a check valve is bad typically it just has crap stuck in it that keeps it from closing. It was taken apart and cleaned out.
Above: As you can see the check valve is a simple device when it is taken apart.
Above: Here is a 1/2″ check valve on the left and a standard 3/8″ check valve on the right.
Above: Here is a 1/2″ check valve assembly ready to install in a car.
Above: Here is a simple upgrade for your system if you have a two pump setup. We call this the devil’s fork. On this setup 1/2 inch check valves are used and the dumps are on the return side of the hydraulic circuit. We’ll have some pictures soon.
Slowdown Valve Pictures
Above: Here is a very small 1/4 inch slowdown valve. These seem to be of good quality but they are very small. A good choice if you are limited in trunk space.
This is a 1/2″ slowdown valve.
You can see this slowdown is very large.