1994/12/19 Caterpillar

New Connecting Rod Assembly Has Increased Fatigue Strength {1218}

Usage:

D11N (4HK, 74Z) Track Type Tractors;
776B (6JC),
776C (2TK),
784B (5RK) Tractors;
777B (4YC),
777C (4XJ),
785 (8GB),
785B (6HK),
789 (9ZC),
789B (7EK),
793 (3SJ),
793B (1HL) Trucks;
994 (9YF) Wheel Loaders;
5130 (7TJ, 5ZL) Excavators

Description of Change: A new connecting rod assembly is used in the 3500 Machine Engines in the above machines. The four connecting rod bolt holes in the new connecting rod assembly are now machined with a near spherical bottom called a "racon profile". This new design decreases the stress which can occur in this area of the connecting rod. The racon profile at the bottom of each hole provides for a higher fatigue strength connecting rod. The new rod design also creates a tighter fit between the rod and the cap. During assembly, the new tighter fit helps eliminate misalignment of the rod and cap which can cause damage to the crankshaft.

Illustration 1. New 101-3281 Connecting Rod Assembly.

Illustration 2. Differences between bottom of connecting rod bolt hole in new and former connecting rod assemblies.

Adaptable To: The new 101-3281 Connecting Rod is a direct replacement for the 7C-8608 Connecting Rod which has been canceled. The new connecting rod is adaptable to first production of the 3500 Machine Engines.

Caterpillar Information System:

1994/12/19 Special Instruction SEHS9734-01 Is Available For Retrofitting R-12 Air Conditioning Systems To R-134a Refrigerant {7320,1809}

1994/12/19 Spacer Plate Is Available To Make Installation Of Permanent Hose Couplings Easier {0684,5057}

1994/12/19 New Filter Used For Screed Burner And Washdown Systems {1274,5642}

1994/12/19 Primary Pressure For The Transmission Pressure Control Group Has Been Increased {0374,3150}

1994/12/19 New Screen Assembly Prevents Large Debris From Transferring Into Differential Compartment {4051,3258}

1994/12/19 Small Cracks Around The Holes In The Front Wheels Can Be Repaired By Welding {4201}

1994/12/19 New Roller Bearings Used In The 8E-9034 Transmission Planetary Group To Improve Service Life {3160}

1994/12/12 New Cylinder Blocks Made From Stronger Alloy{1201}

1994/12/12 New Exhaust Bypass Valve (Wastegate) Used In Exhaust Bypass Group{1057}

1994/12/12 Serviceable Parts For Custom Option Engine Prelube Group{1319}

1994/12/12 Injector Solenoids on Engines Equipped with EUI Are Not Polarity Sensitive{1259}

1994/12/12 Caterpillar Hose Press And Tool Usage{5057,0684}

1994/12/19 New Water And Oil Temperature Regulators Available {1330,1355}

1994/12/19 New Electronic Control Group (Throttle Position Sensor) Has Improved Contact Design {1913}

1994/12/26 New Engine Oil Pressure Gauge And Sender {7455}

1994/12/26 New Bearing Housing Used In Turbocharger Group {1056,1052}

1994/12/26 Information Release Memo PELE0401 Has Information About Remanufactured Hydraulic Piston Pump And Piston Motor Groups {0374,4134,4136,4351,5058,5070,5080,5314,5315,5473}

1994/12/26 New Oil Tube Clamp Assembly Is More Durable and More Resistant to Leakage {1307}

1995/01/16 Special Instruction SEHS9429-01 Available for Spherical Bearings for Bulldozers and Rippers{7551,6050,6313}

1995/01/16 Fuel Injection Pump Change{1251}

1995/01/16 R-134a Refrigerant Used For Air Conditioner Charge{1802,1805}

1995/01/16 Boom Lock Cable Tube Is Now Serviceable{5477,5063}

1995/01/16 Wheel Bearing Check And Adjustment Maintenance Interval{4208}

1995/01/16 Maintenance Intervals Are More Uniform{0375,1300,1350,3250,5600,6600}