The Hydromatic® Brake or Hydrotarder® is a hydrodynamic device that absorbs power by converting mechanical energy into heat in its working fluid, which is normally water. Resistance is created exclusively by fluid friction of the fluid circulated between the vaned pockets of the rotor and stator elements with the conversion of mechanical energy to heat taking place directly within the fluid itself. The amount of mechanical energy that can be absorbed in this manner is dependent upon the quantity and velocity of the fluid in the working chamber.

The internal braking action of the brake is dependent on the fluid flow between the rotor vanes and stator vanes in the brake. When the working chamber is full of fluid, the brake is operating at maximum absorption. The amount of fluid contained in the pocket sections is determined and controlled by the amount of fluid flowing through the brake. With the brake connected to a fluid source or tank, that applies a positive head at the inlet of the brake, and the brake inlet line full open, the brake will be absorbing the maximum energy.

Since the Hydromatic brake functions as a pump, it will draw water from the fluid supply or tank, and pump the water back to the tank, provided the tank is vented to the atmosphere with a positive head pressure.

Increasing the pressure on the brake by restricting the flow from the brake, with a valve in the outlet line
of the brake, will not increase the brake power absorption or provide brake control. Restricting the outlet flow will only increase the internal pressure in the brake, and cause excessive seal wear, reducing the life of the brake seals or possibly blowing out the internal brake seals. Since the brake is absorbing energy and converting the energy into heat in the water, restricting the outlet flow will also increase the outlet water temperature, and steam formation inside the brake may result.

The secondary function of a Hydromatic® Brake water circulating system is to provide controls to permit the driller to vary the brake capacity to meet the rig requirements, The capacity at any speed is adjustable by regulating the quantity of water being circulated between the vaned pockets of the rotor and stators in the working chamber. Depending on the type of installation, infinitely close regulation or regulation in any desired number of steps may be obtained by varying the rate of flow into the brake or varying the level of the water in the circulating system, dependent on the type of brake and type of circulating system.

Any circulating system used must include a means for dissipating the heat from the circulating system at the rate at which it is generated in the water by the retardation of the brake. Heat dissipation may be accomplished by the use of heat exchangers, or by providing a sufficient supply of fluid to act as a heat sink.

All Hydromatic brakes, installed on oil drilling or workover rigs, should be connected to the hoisting drum
with a brake clutch, to disengage the brake when hoisting, and avoid rotating the brake in the reverse direction.

The water system can either be a fluid pump feed system, or a level tank system as shown on the attached
drawings. The pump can be eliminated, on smaller brakes used on mobile workover rigs, and the brake be
gravity fed from an elevated water tank.

The pump feed system is used on smaller brakes including the 262, and the level control system used on
the 341, 342, 342-A, 481, V-200, and V-295.

To obtain maximum performance from the Hydromatic brake, the inlet and outlet line size, should be equal
to or larger than the sizes shown on the water system drawings.

The water pressure, at the brake, should not exceed 25 Psi for 121 thru 22DR brakes, and 15 Psi for all
other sizes of Hydromatic brakes. Higher inlet pressures will only decrease the life of the brake water seals.

Using a pump feed system, the brake is controlled by a valve in the inlet line to the brake. Manual operated
valves such as gate valves or ball valves provide the best control, since the operator can open the valve to a
precise setting. A remote operated valve should only be a ball valve that has automatic positioning. that will
provide the same opening and flow with the same control signal. Air operated butterfly valves are not
recommended due to their poor flow control abilities.