Anything that uses hydraulics has some type of liquid flowing through it. If you fittings that are not right, the system will leak. As more fluid leaks out, there is not enough to create the pressure needed for the hydraulics to work. One of the biggest mistakes people make is using the wrong fitting for a connection within a hydraulic system. Here are a few tips to ensure you have the proper fitting and your system will work the way you need it to.
Most people are under the impression that the size of a fitting is determined by the inside or outside diameter of the tube. The truth is that the size is determined by measuring the diameter of the whole piece, including the threads, and then subtracting ¼ inch. A piece that measures 1 ¼ inch from the outside of the thread on one side to the outside of the thread on the opposite side would be a 1 inch fitting.
The way the threads taper around the tube play an important part in the fit and seal of a tube. Some threads are parallel and evenly spaced the whole length of the threading. Others are tapered, with the threads getting closer together towards the end of the tube. If the threads are tapered, the male part will not be able to fit into the female piece the whole length of the threads without jamming. It the pieces do not fit entirely, you will end up with leaks.
The pitch of the threading is the number of serrations, or threads, within an inch. If the parts are measured with the metric system, the number of threads within a millimeter determines it. It is important to have the same pitch for both the male and female pieces to ensure that no fluid can travel unhindered in the threads and leak out of the system.
When you go to the hardware store to buy a new piece of tubing, taking the piece to be replaced may not be enough to ensure you get what you need. It can be very difficult to judge the exact pitch, size and taper by comparing two pieces side by side. It is best to measure each characteristic first, and then take the piece with you. You will be glad you did the measuring when staring at a bin full of hundreds of similar pieces. Places like Certified Products Co will be able to help you.