1977/10/31 Caterpillar

New Governor Spring Changes Speed Regulation{1264,1286}

Usage:

3408 and 3412 Industrial Engines

SUPPLEMENT: 02/20/78

SERVICE MAGAZINE, OCTOBER 31, 1977, PAGE 5. In the article "New Governor Spring Changes Speed Regulation" there is a reference to 7N1228 Spring for 1500 rpm operation and 7N1295 Spring for 1800 rpm operation. This is not correct. Change 7N1228 Spring to read 7N1295 Spring and change 7N1295 Spring to read 7N1228 Spring.

Also, in the "NOTE" change the identification for 7N1228 Spring to read "--One Light Green Stripe And One Gray End". Change the identification for 7N1295 Spring to read "--One Orange Stripe And One Dark Blue End".

--------------- END SUPPLEMENT ---------------

Description of Change: The governor spring on the above engines has been changed. The new spring changes speed regulation from 10% to 3%. Also, the adjustment screw for the dashpot assembly is turned less to give the engine improved speed stability.

Adaptable As: Direct replacement, but the setting for high and low idle must be reset (adjusted). The initial setting for adjustment screw on the dashpot assembly is as follows:

Turn the adjusting screw in until it has a good seat. Then turn it out one-fourth of a turn.

The 7N1295 Spring is used on the engine models equipped with the fuel injection pump groups that follow:

3408--7N1231--1500 rpm Direct Injection

3408--7N1240--1500 rpm Precombustion Chamber

3412--7N1244--1500 rpm Direct Injection

3412--7N1249--1500 rpm Precombustion Chamber

The 7N1228 Spring is used on the engine models equipped with the fuel injection pump groups that follow:

3408--7N1230--1800 rpm Direct Injection

3408--7N1235--1800 rpm Precombustion Chamber

3412--7N1243--1800 rpm Direct Injection

3412--7N1248--1800 rpm Precombustion Chamber

The new springs were "first used" with the serial numbers that follow and can be installed on all earlier engines.

NOTE: For identification of the new and former springs, use the information that follows:

6N8794 Spring--Both Ends Are Yellow

6N8795 Spring--Both Ends Are Green

7N1228 Spring--One Light Green Stripe And One Gray End

7N1295 Spring--One Orange Stripe And One Dark Blue End

Caterpillar Information System:

1977/10/31 New Hydraulic Flow Meter Has Many Improvements To Make It Easier, Faster And Safer To Use Than The Former Flow Meter{0651,5050}

1977/10/24 Replacement Bearings Have Aluminum Alloy With More Strength{1203,1213,1230}

1977/10/24 New Piston Group Has Improved Iron Band In The Piston Body{1214}

1977/10/24 Adjust Shop Tire Pressures For Operation In Cold Temperatures{4203,4204}

1977/10/24 Assembly Procedure For The 5P4721 Tube (Part Of The 5P4149 Conversion Group And 5P4150 Nozzle Testing Group){0650}

1977/10/17 Vent Tube Added To Jacket Water Aftercooler{1063}

1977/10/17 Separate Parts Of Oil Pump Cover Now Available{1304,1314}

1977/10/17 Improved Main, Thrust And Connecting Rod Bearings Have Aluminum Alloy With More Strength{1230}

1977/10/17 Preparation Of Truck Engines For Cold Weather Operation{1300,1000}

1977/10/17 Fabricated Extension Prevents Fuel "Splash" During Injection Valve Testing{0650,1254}

1977/10/10 If The Fuel Setting Dimension Is More Than 7.00 MM, Remove The End Play Of The Camshaft To Make The Fuel Setting{1257,1286}

1977/10/10 Improved Oversize And Undersize Connecting Rod And Main Bearings With Higher Strength Aluminum Alloy{1203,1219,1230}

1977/10/31 With New 5P7448 Adapter, Earlier Fuel Injection Valves And Nozzles Can Be Tested And Adjusted On The 5P4150 Nozzle Testing Group{0651,1254}

1977/10/31 Some Wobble Is Acceptable In Rubber Vibration Dampers For Crankshafts{1205}

1977/11/07 Crankshaft Support Groups Are Available To Measure Bent Crankshafts{0653,1202}

1977/11/07 Improved Crankshaft Main Bearings And Connecting Rod Bearings With Higher Strength Aluminum Alloy{1203,1219,1230}

1977/11/07 Precision Oil Pump Bearings Now Available{1304}

1977/11/14 New Electric Starting Motor Has Longer Brush Life{1453}

1977/11/14 Exhaust Valves With 30° Face Angle Now Used For Parts Service{1101,1103,1105}

1977/11/14 New Exhaust Manifolds Made Of Stronger Material{1059}

1977/11/21 New Elbow Between Turbocharger And Air Inlet Manifold Has Hole For Ether Starting Aid{1058,1456}

1977/11/21 New Crankshafts Do Not Have Lightening Holes And Lubrication Passages Connected Together{1202,1219}

1977/11/21 Larger Diameter Holes Are Now Used In The Rocker Arm Shaft To Give More Oil Flow To Rocker Arm Bearings{1102}

1977/11/21 Improved Shaft Seal Material Used In All Vane-Type Hydraulic Pumps; Seal Kits Are Canceled{5055}