PEL-JOB EB22 Won’t Dig on Low Revs

[MikePhua]

Overview of the EB22
The PEL-JOB EB22 is a compact mini-excavator built between 1988–1991 (and in extended form as the EB22.4 during 1991–1994) by the French manufacturer Pel-Job, which became part of Volvo Construction Equipment in 1995 . It weighs approximately 2.3–2.4 tonnes, offers a maximum bucket capacity in the range of 0.04–0.06 m³, and is powered by a small Mitsubishi K3E engine producing around 14 kW (≈19 hp) . Its compact design, with narrow tracks and a transport width near 1.45 m, made it ideal for tight job sites and urban landscaping.
The Symptom
Operators discovered that the EB22 would not move its boom, dipper, or bucket when running at low engine revs—despite healthy hydraulic oil levels, functioning blade and tracks, and strong operation when revs were high . The machine’s behavior suggested hydraulic power was available only above a certain RPM threshold, leading to sluggish or unresponsive controls at idle.
Likely Cause
A likely root cause is linked to the machine’s servo control circuits for the boom, dipper, and bucket operations. When the engine RPM is low, hydraulic pressure may not reach the threshold to operate these servo-assisted functions. However, when the tracks are engaged—even at low revs—flow is being generated through the hydraulic system, which helps build enough pressure to allow the other functions to respond . This is consistent with servo-based control systems where some functions are prioritized or dependent on shared pressure sources.
Diagnostic Insights
Key points to investigate include:

• Check whether any hydraulic actuator moves when a track motor is used at low revs. If yes, it confirms that the pressure is there but only when flow is forced .
  
• Inspect the servo circuit pressure using a gauge while operating multiple functions at low RPM.
  
• Oil filter and suction restrictions: Clogged filters or suction lines can prevent proper pressure buildup at low revs .
  
• Test hydraulic pump behavior: Lower engine speed often causes output to drop below servo activation thresholds.
  

Recommendations and Solutions

• Pump and filter maintenance: Clean or replace hydraulic filters and ensure pump suction is unrestricted. A poorly maintained suction line can starve the system at low RPMs.
  
• Monitor inlet and system pressure with gauges to identify the minimum RPM at which controls become responsive.
  
• Inspect servo control valves and load-sensing circuits: These may have threshold settings that can be adjusted or maintained to lower the required RPM for activation.
  
• Consider an auxiliary hydraulic accumulator: Installing an accumulator charged at idle pressure can help servo functions remain responsive when revs are low.
  
• Regular maintenance schedule: Given the EB22’s lightweight hydraulic system, small inefficiencies quickly affect responsiveness. Keep up with oil changes and component checks.
  

Glossary

• Servo control: A hydraulic control mechanism that uses pilot pressure to direct flow; sensitive to minimum pressure levels.
  
• Suction restriction: A blockage or collapse in hydraulic suction lines that limits pump input, especially at low RPMs.
  
• Hydraulic accumulator: A device that stores pressurized fluid to stabilize system pressure during low-demand intervals.
  

Field Note
An operator once shared that his similarly aged compact excavator “felt dead” on hydraulic functions at low idle—but once he nudged the track lever, the entire boom circuit sprang to life. He suspected the servo demand wasn’t being met unless the pump was forced with extra flow, which mirrors the EB22 scenario.
Summary
The EB22's failure to operate its boom, bucket, or dipper at low revs likely stems from insufficient hydraulic pressure in the servo circuits under idle conditions. Operating the track motor adds enough flow to build pressure, enabling the other functions to work. Running diagnostics on hydraulic pressure thresholds, maintaining pump and suction health, and considering a pressure accumulator are all effective strategies to restore full low-rev functionality in this compact excavator.