Class1 107490 - UNI-Governor 107396 107269 software v 6 00 User Manual

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Governor changes engine RPM but will search or hunt (oscillate) when in pressure

mode

There are three programmable parameters that can fine tune governor operation. These are RAMP,

GAIN and SENSITIVITY.

To enter the Menu System:

With [MODE] showing in the Message Center,

Press and hold the IDLE and PRESET switches. While still holding these, press MODE. This puts you

into the MENU system where the RAMP, GAIN and SENS settings can be changed. Scroll through the

3 parameters using the MODE switch. Use the INC or DEC switch to enter that parameter and change

the values. Press PRESET before scrolling to the next parameter.

The governor is shipped from Class1 with all 3 set to 5.

Rate

This parameter controls how much voltage increase or decrease occurs with each press of the

INC or DEC switch. The nominal value of 5 will work on every engine and normally doesn’t need t o

be changed.

GAIN

This parameter controls how fast the voltage will change automatically in response to a pressure

change or when using the PRESET switch. The lower the value, the slower the response. A

value of 5 on some engine-pump combinations will exacerbate the hunt condition.

(The governor is commanding changes faster than the apparatus can follow)

Try a value of 4 first and don’t change any other setting. If this slows the oscillations but they are still

present, then change the SENSitivity setting (described below). The effect of decreasing the GAIN is to

slow down the governor reaction to change. If it becomes too slow, then the governor will not be able to

decrease RPM fast enough when a discharge is closed. Usually 4 is slow enough but in extreme cases

a 3 might be necessary. Do not go to 3 until you have tried a sensitivity change first.

SENS-itivity

This parameter controls how much pressure deviation is allowed before the governor responds.

A setting of 5 allows approximately 5 PSI swings before the governor attempts to restore the set

pressure. The higher the number, the “looser’” the “window”. After setting the GAIN to a 4, set the SENS

to 6 if necessary. Normally this value should never be higher than 7. A setting of 10 allows up to 30 PSI

swings.

Randomly changing values can be counterproductive. Lower the GAIN first, try it and then the SENS

and back to GAIN if necessary. Change by a value of 1 only. If you go too far, it might solve the oscillation

problem but create a response problem. There is no magic set of numbers that will optimize your

installation. Each installation is unique to Engine Torque, Transmission Gearing, Transfer Gear ratio

and pump capacity and design. The parameters are used to match the governor to the apparatus.

A note about two-stage pumps:

In pressure mode, engine RPM is relatively low compared to a single stage pump or the two-

stage in volume mode. This places the engine outside of it’s optimal torque range and small changes in

RPM equate to substantial changes in pressure. This can create two problems.

The engine is slow to respond to commands and the governor starts a lead lag situation that

can result in oscillations. The setup cannot be “tweaked” for best performance in both volume

and pressure.

Snapping a nozzle closed will result in a pressure “spike” that is too fast to be controlled by a

governor or a discharge relief valve. This could also result in an uncontrollable oscillation.

Discretion should be used whenever operating in Pressure Mode, this mode allows for governor opera-

tion in which the governor and engine have the least ability to compensate for pressure changes.