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Description

The Woodward TG-13 and TG-17 are mechanical-hydraulic speed droop governors for controlling steam turbines—applications where isochronous (constant-speed) operation is not required.

The TG-13 and TG-17 governors have a full 40 degrees of maximum terminalshaft travel. Recommended travel from the no load to the full load position is 2/3 of full governor travel. See Figure 1-1 for a graphic representation of maximum work capacity for the governors and related governor terminal shaft travel information.

Governor output is provided through a serrated terminal shaft extending from both sides of the case. The internal pump for the governors is sized to operate over standard speed ranges: • 1100 to 2400 rpm • 2400 to 4000 rpm • 4000 to 6000 rpm The TG-13 governor operates with 1034 kPa (150 psi) internal oil pressure, and the TG-17 operates with 1379 kPa (200 psi) internal oil pressure. Either governor is set to the speed range specified by the customer at time of order. The high-speed governor (4000 to 6000 rpm) may require a heat exchanger in some applications (see end of Chapter 2, When is a Heat Exchanger Necessary?). Both governors are capable of controlling at lower-thanspecified speed range with some loss of output torque and performance.

The governors are available with either a cast-iron case or a die-cast aluminum case. Speed droop is required for stable governor operation. Droop is factory set, but internally adjustable. Two means of speed setting are available. Screw speed setting is standard. Lever speed setting is optional and provided by a serrated shaft assembly extending from both sides of the cover.

Governor drive shaft rotation for both governors is single direction only. In both the cast iron and the die-cast aluminum governors, rotation can be changed in the field. In the cast iron governor, it must be changed internally, and in the diecast aluminum governor, it can be changed externally by removing four screws and rotating the pump housing 180 degrees (see Chapter 2). Governor maintenance is minimal due to few moving parts, weatherproof design, and self-contained oil supply. The governor drive shaft operates a gerotor oil pump. Internal oil pump pressure is regulated by a relief valve/accumulator. The oil sight gauge installed on each side of the governor case makes oil condition and oil-level checking simple.