1987/06/01 Caterpillar

3500 And 3600 Families Of Engines So Equipped

Reference: New Service Manual Module SENR3028-01, "Caterpillar 3161 Governor".

Reference: Engine News, July, 1986; Page 11; "Improvements For Caterpillar 3161 Governors", and February, 1987; Page 4; "Fuel Ratio Control Diaphragms On 3161 Governors".

Several different Caterpillar 3161 Governors have been and are being used in all applications of the 3500 and 3600 Families of Engines. These different governors are all identified by their group numbers on the nameplate, but the differences between each group are not all identifiable. The following charts summarize the major differences to assist you in diagnosing any problems and making adjustments.

List of abbreviation meanings used in all charts:

TR

single slope torque rise

Dual Slope TR

dual slope torque rise used on Caterpillar off-highway trucks

FRC

fuel ratio control

PSC

pneumatic speed control

MSO

manual shutoff

ESA

electric speed adjust motor

ESO

electrical shutoff

Int. Droop

internally adjustable droop-adjustment requires removal of cover

Ext. Droop

externally adjustable droop

Low Droop

range of droop adjustment about 0 to 5.5%

Mid Droop

range of droop adjustment about 1.4 to 6.2%

High Droop

range of droop adjustment about 4.1 to 10%

NOTE: All 3161 Governors on the 3600 Family have higher pressures and higher output torque than 3161 Governors on the 3500 Family. The first reference article on governor improvements also applies, although the 3600 Family is not listed in the article title.

Servicing Parts For 3161 Governors

Many parts and optional parts not critical to these governors are easily replaced. See following list.

... All electrical, mechanical, or pressure shutoff groups.

... The pneumatic speed control group.

... The fuel ratio control group. See the second reference article for servicing the lower and upper diaphragms.

... The oil supply orifice.

... The oil pump group.

... The high and low idle stop screws and lever.

... The various covers, plugs and seals on the outside of the governor.

... Replacement of the compensating springs and pistons requires removing the base.

The first three items are available as preassembled groups. The following fuel ratio control groups are used. See Chart E. The only difference is the spring that controls the slope of the maximum rack versus boost characteristic.

Replacement of some other parts requires opening the governor and/or special care.

All other work on all 3161 Governors requires a governor test stand. Only servicemen who are trained in and understand the governor operation should use the test stand.