Governors Flashcards
True or false: Governors are mechanisms used to control and maintain the speed of a prime mover.
True
With governors, it is very important to verify that the overspeed trip functions correctly and that the fuel or steam supply does not pass by the trip valve. How is this done on small steam turbines?
By manually tripping the overspeed system and partially opening the supply valve.
If any steam or air passes by the trip valve, the overspeed trip may need adjustments or the trip valve and seat may need repair.
How would a governor shut off an engine in an overspeed situation?
By shutting the air inlet to the intake manifold.
True or false: Do not attempt to run up a prime mover without having a functional emergency trip system.
True
When placing a new governor into service, typically the only requirement for the millwright is to fill the governor reservoir with the proper oil and adjust the speed at initial start up. What is the recommendation for the speed setting at start up?
Set the speed lower than required, and increase as needed.
True or false: Typically, governors can be serviced in-house.
False
Some less complex mechanical governors can be serviced in-house, but most require being sent back to the OEM for servicing.
How can the operating speed be adjusted on simple mechanical governors?
By adjusting spring tension
The speed setting can be adjusted by varying the compressive force on the spring.
What are three things that should be checked on mechanical governors during a prime mover overhaul?
- Knife edges and pivot points are in good condition
- Sliding parts are not binding or sticking when moving
- Anti-friction bearings have no wear
This is for a prime mover overhaul ⟶ a governor overhaul should be completed by the OEM.
What does dirt or sludge in the housing of a governor usually indicate?
That it is time to dismantle and governor and perform a thorough cleaning and inspection.
In mechanical-hydraulic governors, large quantities of oil are continually circulated through the hydraulic side of the governor system. What issues can be caused by dirt and grit in the system?
Sticky relays, valves, or servo rams.
When should governors be overhauled (2 things)?
- During an engine or turbine overhaul
- Anytime there is contaimination in the hydraulic system
What are four things that should be done/checked when dismantling a governor and inspecting it for wear or damage?
- Replace all gaskets and seals
- Check linkages for smooth operation
- Clean and check all lines and passageways for blockages
- Flush all parts with the correct hydraulic oil
Some of the seals may break down in the presence of wrong oils.
What are six items that should be completed during routine preventative maintenance of a governor?
- Lubricate all linkages
- Replace worn parts
- Check all clearances
- Inspect the throttle valve
- Clean and inspect the trip valve
- Replace valve stem packing as needed
________ automatically control the speed of a prime mover under varying load conditions
Governors
What are three functions that a governor performs when automatically controlling the speed of a primer mover?
- Maintain the selected speed
- Limit the slow and fast speeds
- Shut down the prime mover if it over speeds
Identify the detection, transmission, and correction of this basic law mower governor:
Detection → vane
Transmission → the linkage
Correction → throttle valve
At start up, what would be the position of the fuel admission valve (steam admission valve, throttle valve, etc.) when controlled by a governor?
Fully open
The valve would be fully open
True or false: Governors operate on the principle of two opposing forces acting against each other.
True
These forces could be springs vs. airflow, etc.
True or false: Governors are fully open at start.
True
What three components are common to all types of automatic governor control?
- Detection
- Transmission
- Correction
All governors must include these three components.
True or false: Most governors on spark ignition engines allow an engine to fire steadily regardless of load, while varying the fuel to air ratio, either by speeding up or slowing down the engine.
True
What valve does the governor in a spark ignition engine actuate to control the speed?
The throttle valve
This valve is located in the intake passage between the carburetor and the manifold and controls the air-fuel mixture entering the engine.
What causes the diaphragm of a governor in a spark ignition engine to move?
Vacuum
Airflow into the engine ↑ = Vacuum ↑
When it comes to governors, what is the detection component of the governor?
This is what detects a change in the operating conditions of the prime mover
It is not the change itself (RPM, vacuum, airflow, etc.) rather what detects this change (diaphragm, flyweights, spring, etc.).