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Machine Overview & Hydraulic System Fundamentals
The Cat 307 series (including 307, 307C, 307E2, and 307.5) features a load‑sensing hydraulic system with a variable‑displacement axial‑piston pump, designed to automatically match hydraulic output to engine demand. This configuration delivers precision control and fuel efficiency by adjusting pump flow and pressure as needed .
Standard Operating Pressures (at nominal engine speed ~2,400 rpm)
These pressure figures represent system limits under load:
• Equipment (boom, stick, bucket): 4,134 psi (285 bar)
• Travel motors: 4,134 psi (285 bar)
• Swing circuit: 3,626 psi (250 bar)
• Auxiliary circuits (primary & secondary): Flow and pressure identical to equipment circuit (~4,134 psi, 131 L/min primary, 33 L/min secondary)
In earlier 307C units, spec sheets differ slightly with travel pressure listed at around 4,400 psi (305 bar) depending on specific model and configuration .
Maximum Hydraulic Flow Capabilities
Pump output capacities vary across models:
• Cat 307 and 307E2: ~154 L/min (40.9 gal/min) at 2,400 rpm
• Cat 307.5: ~167 L/min (44 gal/min) at 2,400 rpm
Digging Forces
• Standard stick: ~37–38 kN (8,340–8,504 lb)
• Long stick (307.5): ~33.7 kN (7,579 lb)
Lift Capacities (ISO‑standard limits)
307 series machines adhere to ISO 10567:2007 lift capacity standards, strictly operating within roughly 87% of hydraulic lifting capacity or 75% tipping capacity. Actual lift charts are available for each configuration but generally follow structured rating tables .
Summary Table of Hydraulic Specs
• Operating Pressure – Equipment / Travel: 4,134 psi (285 bar)
• Swing Circuit Pressure: 3,626 psi (250 bar)
• Pump Flow:
– 307/307E2: ~154 L/min (40.9 gal/min)
– 307.5: ~167 L/min (44 gal/min)
• Auxiliary Flow: Primary ~131 L/min, Secondary ~33 L/min (both at ~4,134 psi)
• Stick Dig Force: ~37.1–37.8 kN (8,300–8,500 lb)
• Bucket Dig Force: ~50–55 kN (11,000–12,300 lb)
• Swing Speed: ~10–11 rpm
Pressure vs. Flow Behavior
As a load‑sensing system, the Cat variable‑displacement pump reduces pressure as flow increases under load—therefore flow and pressure are inversely related, and cannot be achieved simultaneously at maximum values .
Field Applications & Testing Anecdote
During hydraulic horsepower testing, operators on 307C units used aftermarket pressure kits to verify that equipment pressure remained near specs under high hydraulic demand, while flow varied based on function. This confirmed the behavior characteristic of load-sensing systems—peak pressures during boom work, and reduced pressures with high-volume auxiliary use .
Terminology Clarified
• Load‑Sensing Hydraulics: System that automatically limits pump pressure and adjusts flow to match demand, improving efficiency.
• Variable‑Displacement Pump: Hydraulic pump which changes its output volume as needed.
• Primary/Secondary Aux Circuits: Dedicated circuits for auxiliary tools attachment, with flow independent from main boom/stick circuits.
• Pressure‑Flow Tradeoff: Under load, the pump allows flow to rise at the expense of reduced pressure to prevent overloading engine/pump.
Why These Specs Matter
Knowing precise operating pressures and flow capacities enables reliable troubleshooting—such as verifying if travel motors are starved of flow or if boom operation is limited by low pressure. When using pressure gauges on test ports, correct comparisons to spec values are essential.
Conclusion
Whether working on a Cat 307, 307C, 307E2, or 307.5, the key hydraulic system values remain consistent:
The Cat 307 series (including 307, 307C, 307E2, and 307.5) features a load‑sensing hydraulic system with a variable‑displacement axial‑piston pump, designed to automatically match hydraulic output to engine demand. This configuration delivers precision control and fuel efficiency by adjusting pump flow and pressure as needed .
Standard Operating Pressures (at nominal engine speed ~2,400 rpm)
These pressure figures represent system limits under load:
• Equipment (boom, stick, bucket): 4,134 psi (285 bar)
• Travel motors: 4,134 psi (285 bar)
• Swing circuit: 3,626 psi (250 bar)
• Auxiliary circuits (primary & secondary): Flow and pressure identical to equipment circuit (~4,134 psi, 131 L/min primary, 33 L/min secondary)
In earlier 307C units, spec sheets differ slightly with travel pressure listed at around 4,400 psi (305 bar) depending on specific model and configuration .
Maximum Hydraulic Flow Capabilities
Pump output capacities vary across models:
• Cat 307 and 307E2: ~154 L/min (40.9 gal/min) at 2,400 rpm
• Cat 307.5: ~167 L/min (44 gal/min) at 2,400 rpm
Digging Forces
• Standard stick: ~37–38 kN (8,340–8,504 lb)
• Long stick (307.5): ~33.7 kN (7,579 lb)
Lift Capacities (ISO‑standard limits)
307 series machines adhere to ISO 10567:2007 lift capacity standards, strictly operating within roughly 87% of hydraulic lifting capacity or 75% tipping capacity. Actual lift charts are available for each configuration but generally follow structured rating tables .
Summary Table of Hydraulic Specs
• Operating Pressure – Equipment / Travel: 4,134 psi (285 bar)
• Swing Circuit Pressure: 3,626 psi (250 bar)
• Pump Flow:
– 307/307E2: ~154 L/min (40.9 gal/min)
– 307.5: ~167 L/min (44 gal/min)
• Auxiliary Flow: Primary ~131 L/min, Secondary ~33 L/min (both at ~4,134 psi)
• Stick Dig Force: ~37.1–37.8 kN (8,300–8,500 lb)
• Bucket Dig Force: ~50–55 kN (11,000–12,300 lb)
• Swing Speed: ~10–11 rpm
Pressure vs. Flow Behavior
As a load‑sensing system, the Cat variable‑displacement pump reduces pressure as flow increases under load—therefore flow and pressure are inversely related, and cannot be achieved simultaneously at maximum values .
Field Applications & Testing Anecdote
During hydraulic horsepower testing, operators on 307C units used aftermarket pressure kits to verify that equipment pressure remained near specs under high hydraulic demand, while flow varied based on function. This confirmed the behavior characteristic of load-sensing systems—peak pressures during boom work, and reduced pressures with high-volume auxiliary use .
Terminology Clarified
• Load‑Sensing Hydraulics: System that automatically limits pump pressure and adjusts flow to match demand, improving efficiency.
• Variable‑Displacement Pump: Hydraulic pump which changes its output volume as needed.
• Primary/Secondary Aux Circuits: Dedicated circuits for auxiliary tools attachment, with flow independent from main boom/stick circuits.
• Pressure‑Flow Tradeoff: Under load, the pump allows flow to rise at the expense of reduced pressure to prevent overloading engine/pump.
Why These Specs Matter
Knowing precise operating pressures and flow capacities enables reliable troubleshooting—such as verifying if travel motors are starved of flow or if boom operation is limited by low pressure. When using pressure gauges on test ports, correct comparisons to spec values are essential.
Conclusion
Whether working on a Cat 307, 307C, 307E2, or 307.5, the key hydraulic system values remain consistent:
- ~4,134 psi for equipment and travel pressure
- ~3,626 psi for swing pressure
- Flow up to ~167 L/min depending on model
- Aux circuits match equipment pressure but split flows
