SANY SSY005661438 SY600/SY650 Final Drive Sprocket Wheel Assembly

Product Specifications

Technical Description: SANY SSY005661438 SY650 Final Drive Sprocket Assembly

1. General Overview & Functional Definition

The SANY SSY005661438 SY650 Final Drive Sprocket Assembly is an integrated, dual-function power train component that combines the final reduction gearbox with the drive sprocket. It is the definitive power-output unit for the track system on the SANY SY650 hydraulic excavator. This assembly is responsible for converting high-speed hydraulic power into the high-torque, low-speed rotational force required to propel the machine.

Its primary functions are:

• Final Reduction & Torque Multiplication: Houses a multi-stage planetary gear reduction system to dramatically increase the output torque from the hydraulic motor.

• Power Transmission & Traction Generation: The sprocket directly meshes with the track chain bushings to pull the track, generating the machine's forward and reverse propulsion.

• Integrated Structural Support: Serves as a major structural element of the undercarriage, supporting the rear of the track frame and reacting against the immense forces from track tension and drive torque.

• Sealed Lubrication System: Provides a sealed, oil-bath environment for the high-speed gears and bearings, ensuring efficient lubrication, heat dissipation, and protection from external contaminants.

2. Detailed Component Breakdown & Technical Specifications

This assembly is a complex, pre-assembled unit where the sprocket and final drive are serviced as a single entity or a matched set.

2.1. Sprocket (Output Ring Gear)

• Material & Manufacturing: Forged from high-carbon, high-manganese steel (e.g., 50Mn or equivalent) to withstand extreme impact and abrasive wear. The forging process ensures superior grain structure for fatigue resistance.

• Design Features:

  • Precision Tooth Profile: The teeth are machined to a specific pressure angle and pitch to ensure perfect, non-slip engagement with the track chain bushings. The tooth profile is crucial for efficient power transfer and minimizing noise.

  • Advanced Heat Treatment: The tooth flanks and roots undergo induction hardening or flame hardening to achieve a high surface hardness (58-62 HRC) for maximum wear resistance, while the core of the tooth remains tough to absorb shock loads.

  • Integrated or Bolted Design: In this integrated assembly, the sprocket is either spline-coupled or bolted directly to the planetary carrier of the final drive, ensuring a solid connection for torque transmission.

2.2. Final Drive Gearbox

• Planetary Gear Set: The core of the assembly, typically consisting of two or three stages of planetary reduction. This compact, concentric design is ideal for achieving high reduction ratios and distributing loads evenly across multiple gears.

  • Components: Includes a sun gear (input), multiple planet gears, planet carriers, and a ring gear (stationary within the housing).

• Input Shaft & Hub: The interface for the hydraulic motor. It is splined to accept the motor's output shaft and is supported by high-precision bearings.

• Final Drive Housing: A robust, cast alloy steel housing that encloses all gear components. It is designed to be rigid, preventing misalignment under load, and includes mounting flanges for attachment to the track frame.

2.3. Bearing System

• Configuration: Utilizes a combination of Tapered Roller Bearings and Cylindrical Roller Bearings.

• Function:

  • Tapered Roller Bearings: Primarily used to handle the immense radial loads from the machine's weight and the significant axial (thrust) loads generated during turning and track tension.

  • High-Capacity Design: All bearings are selected for their ultra-high dynamic load rating to ensure longevity under continuous heavy loads.

2.4. Sealing System

• Configuration: A multi-layered, critical system to protect the internal gears and separate the gear oil from the external environment.

  • Primary Dynamic Seal: A large-diameter, heavy-duty floating face seal or radial lip seal is located between the rotating sprocket and the stationary housing. This seal operates in the most contaminated area, excluding mud, water, and abrasives.

  • Input Shaft Seal: A separate seal prevents gear oil from leaking past the input shaft where the hydraulic motor attaches.

  • Breather: A pressure-equalizing breather is included to prevent pressure buildup from thermal expansion of the gear oil.

2.5. Lubrication System

• The assembly is filled with a specific type and volume of Extreme Pressure (EP) Hypoid Gear Oil (e.g., API GL-5). This oil lubricates the gears and bearings, dissipates heat, and protects against wear and corrosion.

3. Integration within the SY650 Undercarriage System

The Final Drive Sprocket Assembly is the terminus of the machine's propulsion system:

• Interface with Hydraulic System: It is bolted directly to the Travel Motor, which provides the hydraulic input power.

• Interface with Track Frame: It is bolted to the rear of the Track Roller Frame, forming a rigid structural component.

• Interface with Track Chain: It drives the Track Chain by meshing with the track bushings, working in opposition to the Front Idler to create a continuous track loop.

4. Critical Performance & Maintenance Parameters

• Sprocket Wear Monitoring: The primary wear point is the sprocket tooth profile. Wear should be monitored for "hooking" or a concave profile. SANY provides maximum allowable wear limits. Operating a worn sprocket against a new track chain (or vice-versa) causes catastrophic accelerated wear due to pitch mismatch.

• Gear Oil Analysis: Regular checking of the oil level and periodic oil analysis are critical. The presence of metal particles (indicating internal wear) or water (indicating seal failure) are serious warning signs.

• Seal Integrity: External inspection for oil leaks around the sprocket seal or input shaft is essential. A leaking main seal will lead to rapid failure of both the final drive (from lack of lubrication) and the track chain (from oil contamination).

• Bolt Integrity: All mounting bolts must be maintained at the manufacturer's specified torque to prevent loosening from the tremendous vibration and shock loads.

5. Failure Mode and Effects Analysis (FMEA)

• Accelerated Sprocket Tooth Wear: Caused by improper track tension, misaligned undercarriage, or mismatched track chain.

• Tooth Chipping or Fracture: Resulting from extreme shock loads or material fatigue.

• Bearing Failure: Often a secondary failure caused by seal failure (contamination), loss of lubrication, or excessive axial loads.

• Gear Tooth Pitting/Spalling: A surface fatigue failure caused by repeated high-contact stresses over time.

• Input Shaft Seal Failure: Leads to loss of gear oil and contamination ingress, resulting in rapid internal damage.