POWER-CO.NET   

Governors. Why?? Who needs them?

When  James Watt invented the steam engine he found it to be difficult to control the speed of  his new engine manually.  

He also found that it was hard to keep the speed down to a safe level when load was suddenly  removed and to speed it up upon with a load increase. What he developed was the first engine governor.  By  using centrifugal force against gravity in the diagram below  the faster the weights spin the further they want to swing out, shown by the red arrow lifting the the green bobbin due to the linkages from the ball arms. This pulls the blue rod to the right and thus reduces the flow  steam to a steam engine of fuel to a diesel. Gravity acts against fly weights. in this case gravity wants to speed the engine up while centrifugal force wants to slow the engine down . 

                        Watts Fly ball governor 

The next step in the evolution was to replace gravity with a variable spring. now we can operate in any position as it does not rely on gravity.

we can change the desired speed by placing more force on the spring for the weights to overcome or establish a point of balance.  

                                                                                                    Fly weights through the cam gear. More speed pulls on the sleeve 

The other thing that Watt needed was to keep the engine at a constant speed and to ad power as load increased and to decrease power as load decreased.  

FACT: a diesel engine can double it's rpm every second. Be very careful if you move the fuel rack on the engines manually. It is not a good idea to do this on any diesel.. Due to the fact of being able to double their RPM every second and the heavy reciprocating members with in these and other diesel engines  the max rpm is substantially  lower that of  a gas engine. If they are turned to fast the parts will be over stressed and fail catastrophically.  I remember touring the engine room on a large fairy the two main drive engines were V12 Enterprise diesels  and they were tached out at 450Rpm.   Big moving parts.

So we have mentioned:

1: Prevent over speeding of engine (Set maximum engine speed)

2: Hold engine speed steady

3: Ad power as load increases 

4:Decrease power as load is decreased 

5: Set and hold minimum engine speed 

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