Insufficient machine power generally falls into two categories:

1. Engine power deficiency

2. Overload in the work system or transmission

Sometimes both conditions occur simultaneously. To diagnose accurately, machine performance parameters must be known.

I. Engine Power Deficiency

Main indicators:

• Engine cannot reach rated speed under maximum load; speed is below rated value, often accompanied by heavy black smoke or stalling.

Diagnostic methods:

1. Check load conditions

   • If reducing the load restores normal engine performance, the cause is overload.

   • Note: Arbitrarily increasing hydraulic system pressure can also cause engine overload.

2. Observe engine speed and machine motion

   • If the engine speed exceeds rated RPM but machine motion is slower than standard → the engine is underutilized.

3. Reference machine performance parameters

   • Examples: maximum speed of fully loaded mining trucks, lift/unload times of wheel loaders, empty travel speed of bulldozers, cycle times of excavator movements.

   • Use a stopwatch to ensure accurate measurements.

4. Turbocharged engine check

   • Measure instantaneous maximum intake boost to assess engine output.

II. Work System or Transmission Overload

Main indicators:

• Engine produces black smoke at rated RPM, with possible RPM drops or stalling.

• Machine action performance exceeds original specifications (overload in hydraulic or hydrostatic systems).

Diagnostic method:

• Use a stopwatch to measure machine cycle times. Small decreases indicate system overload rather than engine deficiency.

III. Combined Engine Performance Decline and System Overload

Indicators:

• Machine cannot complete test cycles, engine stalls or shuts down, usually without heavy black smoke.

Diagnostic methods:

1. Circuit-by-circuit check

   • Exclude circuits that are functioning normally; the remaining circuit is likely at fault.

2. Variable hydraulic system issues are common

   • System cannot reduce to minimum flow → likely variable pump or control system fault.

3. Fixed-displacement pump systems rarely fail this way

   • Usually, pump flow decreases, causing slower movement without engine stalling.

4. Performance parameter measurement

   • Machines of the same tonnage generally have similar action times; deviations indicate potential issues.

   • Machines that drift during travel require additional checks.

IV. On-Site Operational Advice

• Bring a stopwatch and manual; measure machine cycle times against standard parameters.

• Rule out abnormal loads before assessing engine output.

• Check fuel circuits and filters for blockages, as these are the simplest and most common causes.

• Experienced technicians can quickly locate issues by analyzing machine action and engine behavior.

Summary:
Insufficient power is rarely caused by a single fault. It usually results from interaction between engine output and work system load. A stepwise approach — evaluate load, measure performance parameters, then inspect circuits or system faults — is the most reliable method in the field.