A11VO for roadheader

In the extreme environment of a roadheader—characterized by high dust levels, heavy loads, and confined spaces—the A11VO serves as the core power source for the hydraulic system, primarily responsible for supplying power to the cutting head rotation, travel mechanisms, and loading mechanisms.

First, Adaptation to Roadheader Operating Conditions

1. Extreme Shock Resistance Design: The roadheader’s cutting head generates severe random shock loads when breaking rock. The A11VO’s swashplate design offers excellent damping characteristics, effectively absorbing mechanical shocks transmitted through the hydraulic fluid from cutting vibrations back to the pump body, thereby protecting the bearings from fracturing due to high-frequency vibrations.

2. LRDU Electro-Hydraulic Proportional Power Control: Roadheaders experience extreme load fluctuations (switching between hard rock and soft soil).

Electronic Control Priority: By sending signals to the A11VO’s proportional solenoid valve, the main pump’s power can be dynamically adjusted from the operator’s cab. This ensures that displacement is automatically reduced to increase torque during hard rock operations, preventing motor overload.

Remote Cut-off: When the cutter head becomes jammed by hard rock (stalled), the main pump can cut off pressure, instantly reducing displacement to zero to protect the machine’s entire electrical system.

3. Compact Series Design Roadheaders have a long, narrow body with extremely limited internal installation space. The A11VO’s excellent through-shaft drive capability allows for the mounting of multi-stage gear pumps or small plunger pumps behind the main pump to drive the spray dust suppression system and track travel, reducing the complexity of the power take-off (PTO).

Second, Faults and Maintenance of the A11VO for Roadheaders

In the high-load, dusty environment of roadheaders, faults in the A11VO pump typically manifest as flow/pressure logic failures or hardware wear.

Core Fault Analysis

1. No Pressure or Only Standby Pressure

Symptoms: The cutting head does not move or moves extremely slowly.

Causes: The LS (load-sensing) valve spool is stuck in the fully open position, preventing the pump swashplate from detecting the load signal and returning to neutral; or the DR (pressure cut-off) valve is improperly adjusted, causing premature pressure relief.

2. High Pressure Immediately Upon Startup (Overpressure Phenomenon)

Symptoms: Immediately after starting the motor, the pump reaches the cut-off pressure, causing the motor to trip due to overload.

Cause: The LS valve spool is stuck in the closed position, or abnormal feedback pressure at its control port (Port X) causes the system to misjudge the load.

3. Insufficient Flow Output

Symptom: Tunneling speed slows significantly as the load increases.

Cause: The power setting of the LR (Constant Power) valve is too low; or severe wear between the pump’s internal pistons and distribution plate has caused internal leakage to exceed limits.

Key Maintenance Procedures

1. Valve Assembly Cleaning: For stuck LS/DR/LR spools, do not force disassembly. Soak in diesel fuel and gently tap to dislodge them. Check whether the damping orifices are clogged with dust or sludge.

2. Adjustment Screw Logic:

Flow Adjustment: Loosen the minimum displacement adjustment screw outward to increase flow; tighten it inward to decrease flow.

Pressure Shut-off: If the shut-off pressure is unstable, focus on inspecting the fatigue of the DR valve spring.

3. Hardware Inspection: Check the plunger ball head and slide shoe for signs of galling. In the high-vibration environment of a roadheader, a loose slide shoe is the primary cause of abnormal noise in the A11VO.

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