Injector Brake Hydraulic Circuit

Objective

Today we are going to examine a typical fail-safe brake circuit for a coiled tubing injector.

This will include an explanation of the components that make up the hydraulic circuit.

As well as list of causes and remedies for a brake that will not fully apply, or that will not release.

The Brake?

In the brake component session (Injector Fail-Safe Brake) we looked at the plates and disks of the fail-safe brake and noticed that they are spring applied (fail-safe) and released by hydraulic pressure.

In this session we will examine the hydraulic circuitry that controls the brake release pressure.

Automatic or Manual Control?

There are three possible control schemes for the injector brake.

Automatic:

Many injectors have a set of brake control valves installed, that automatically release the brake when the operator sets the controls (the stick) for the injector to provide in-hole or out-hole motion.

Manual:

Some coiled tubing units have no brake control valves on the injector.

The operator has one master valve in the control cabin and the function to apply or release the brake is a manual one.

Combination:

Most coiled tubing units have both the automatic brake release/apply system, together with a manual override valve for the operator.

The manual valve is useful for emergencies or for any circumstance where the operator wants the injector movement, positively locked out for an extended period, worry free.