CAT 296-1370 TRUNNION-GD

CAT 296-1370 YM is a planetary gear shaft assembly (also known as a cross shaft/trunnion) for Caterpillar engineering machinery. It is adapted for the slewing mechanism, travel gearbox, or working device gearbox of mini excavators and loaders, used for transmitting torque, positioning planetary gears, and balancing loads. The following is precise technical and application information:

Core Technical Parameters
Item Details
Part Model: CAT 296-1370 (2961370) YM Gear Shaft Assembly, weighing approximately 2.86 kg (6.3 lb). The assembly includes the gear shaft, planetary gears, needle roller bearings, retaining rings, oil seals, and locating keys.

Core Materials: Gear Shaft (20CrMnTi carburized steel, carburized layer depth 1.2-1.5 mm, surface hardness HRC 58-62, core hardness HRC 30-35); Planetary Gears (42CrMo tempered steel, hardness HB 260-300, tooth surface carburized and quenched HRC). 55-60); Needle roller bearing (GCr15 bearing steel, precision grade P6); Oil seal (FKM fluororubber, temperature resistance -20℃ to +200℃)

Key Dimensions: Overall shaft length 220 mm, gear module 4, number of teeth 18, pressure angle 20°, pitch circle diameter 72 mm, tooth width 35 mm, journal diameter 35 mm, locating key width 8 mm, keyway depth 4 mm, bearing mounting groove diameter 50 mm, retaining ring groove width 3 mm, planetary carrier bore diameter 38 mm

Rated Parameters: Operating temperature -40℃ to +150℃, rated torque 2.8 kN・m, maximum speed 2500 r/min, rated load 22 kN, compatible grease NLGI 2 lithium-based grease, ultimate impact load 50 kN

Suitable Operating Conditions A medium-load, continuously operating planetary transmission system, suitable for vibration and shock conditions, used for power transmission and speed regulation, compatible with both hydraulic and gear oil operating conditions in construction machinery.

Compatible Models: CAT 303CR/304CR mini excavator (slewing gearbox), 903C loader (working device gearbox), 216B3 skid steer loader (travel drive axle), 305.5E2 excavator (stick reduction mechanism)

Supporting Components: Compatible needle roller bearings 398-9799, retaining rings 3G-1681, oil seals 453-2164, bolts 106-7773 (M12×30), grease nipples 1U-8878
Core Functions and Structural Features:
Power Transmission: Power is transmitted through gear meshing, achieving speed reduction and torque increase. Compatible with planetary transmission systems, ensuring smooth power output and improving transmission efficiency.

**Positioning Support:** The gear shaft positions the planetary gears, working with needle roller bearings to reduce friction and ensure precise meshing between the planetary gears, sun gear, and ring gear, preventing uneven wear on the gear surfaces.

**Load Balancing:** The symmetrical structural design balances the radial load during planetary gear operation, reducing shaft vibration and extending the transmission system’s lifespan.

**Sealing Protection:** Integrated oil seals and retaining rings prevent lubricant leakage and external dirt and sand intrusion, suitable for dusty and humid engineering machinery conditions.

**Integrated Design:** The assembly structure includes gears, shafts, bearings, and seals, facilitating installation, reducing on-site assembly errors, and improving maintenance efficiency.

**Installation and Maintenance Points:**
**Installation Specifications:** Clean components and mounting surfaces, removing burrs and oil contaminants. Inspect gear teeth for damage, journals for scratches, bearings for jamming, and oil seals for damage.

Heat-fit bearings (oil temperature 80-100℃). After press-fitting, the bearing clearance should be 0.02-0.05 mm. Assemble the gear shaft and planetary carrier positioning keys in place, and pre-tighten bolts symmetrically (torque 90 N·m). Fill the gear oil tank and run it for 10 minutes. Check the oil temperature and for leaks. An oil temperature ≤85℃ is normal.

Maintenance Recommendations: Check the wear of the gear shaft and planetary gears every 500 working hours. Replace the components if the tooth surface wear is >0.2 mm or the bearing clearance is >0.1 mm.

Change the gear oil regularly to keep it clean and prevent oil contamination that could accelerate tooth and bearing wear.