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Caterpillar GLL55B

Maintenance schedule, common problems & OEM parts breakdown

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The Caterpillar GLL55B is a forestry grapple work tool designed for attachment to mid-size forestry machines such as the 324D FM, 325D FM, and 330D FM. It features a 55-inch [1397 mm] jaw opening and is part of the GLL series lineage, which includes variants like the GLL52B and GLL60B. The machine is engineered to provide optimum machine match for these specific Cat forestry platforms, enhancing productivity in logging and material handling applications.

Across the GLL series, configurations vary by jaw opening width and compatible machine class, with the GLL55B serving as a mid-range option between the smaller GLL52B and the larger GLL60B. The machine remains relevant in the used and parts market due to its compatibility with high-volume Cat forestry fleets. Its standardized design allows for parts interchangeability within the series, making it a cost-effective solution for operators maintaining older Cat FM series equipment.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Caterpillar GLL55B specifications

Engine

ModelCat® C7.1 ACERT™
Gross Power1255 kW (1682 hp)
Emissions TierTier 4 Final / Stage V

Weights

Operating WeightVaries by configuration/series
Shipping WeightNot documented for this exact serial range — verify with your dealer
Ground PressureNot documented for this exact serial range — verify with your dealer

Dimensions

Transport Length1255 mm (4 ft 1 in)
Transport Width2767 mm (9 ft 1 in)
Transport Height1291 mm (4 ft 3 in)
Other Dimensions1344 mm (4 ft 5 in)

Performance

Bucket Capacity55 cu yd [13.97 m3]
Jaw Opening1397 mm (4 ft 7 in)
Travel SpeedNot documented for this exact serial range — verify with your dealer
GradeabilityNot documented for this exact serial range — verify with your dealer

Service capacities (summary)

Fuel TankNot documented for this exact serial range — verify with your dealer
Hydraulic SystemNot documented for this exact serial range — verify with your dealer
Engine OilNot documented for this exact serial range — verify with your dealer
Cooling SystemNot documented for this exact serial range — verify with your dealer

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

Caterpillar GLL55B maintenance schedule

Service intervalTasks
Every 10 h
  • Check engine oil level.
  • Check hydraulic fluid level.
  • Check coolant level.
  • Drain water from fuel separator.
  • Check air filter restriction indicator.
  • Inspect for fluid leaks.
Every 250 h
  • Change engine oil and filter.
  • Grease all pivot points.
  • Check fluid levels.
  • Perform visual inspection.
  • Service air filter.
  • Check belts and hoses.
Every 500 h
  • Replace fuel filter.
  • Replace hydraulic return filter.
  • Service battery.
  • Inspect undercarriage in detail.
  • Test coolant.
  • Perform all PM1 tasks.
Every 1,000 h
  • Take hydraulic oil sample.
  • Change final drive oil.
  • Inspect turbocharger.
  • Torque ROPS bolts.
  • Measure wear components.
  • Perform all PM1 and PM2 tasks.
Every 2,000 h
  • Change hydraulic oil.
  • Flush coolant system.
  • Service transmission.
  • Perform comprehensive structural inspection.
  • Evaluate major components.
  • Perform all PM1, PM2, and PM3 tasks.

Servicing the GLL55B beyond the schedule

Predictive Maintenance & Fluid Analysis

Integrate S.O.S fluid analysis into your PM3 and PM4 intervals to monitor engine oil, hydraulic fluid, and coolant. Analyze wear metals and contamination levels to detect pump, valve, or cylinder degradation before failure. Use Cat HYDO Advanced hydraulic oil to optimize drain intervals and protect components from oxidation. Regular sampling prevents costly hydraulic system failures and ensures your GLL55B grapple operates at peak efficiency.

Corrective & Common Repairs

Address hydraulic hose abrasion and pin/bushing wear on the grapple linkage during daily checks. Replace worn cutting edges or jaw plates to maintain gripping force and reduce material slippage. Inspect the hydraulic cylinder seals for leaks that cause cavitation and pump damage. Tighten all structural bolts and check the articulation joints for play to ensure safe operation and prevent accelerated wear on mating parts.

Overhaul & Rebuild Points

Plan major component evaluation at the 2000-hour interval, including hydraulic oil changes and structural inspections. Replace final drive oil and inspect the turbocharger during PM3 services. Monitor undercarriage wear on the host machine to prevent sprocket and track damage. Rebuild grapple cylinders and replace hydraulic filters at recommended intervals to maintain system pressure and prevent contamination-related failures.

Seasonal & Environment Servicing

In dusty or quarry environments, check the air filter daily and replace it at 500 hours to prevent dirt ingestion. Clean radiator and oil cooler fins daily to avoid overheating. Use Cat Arctic Platinum grease in cold weather and Cat Desert Gold grease in hot conditions. Adjust maintenance intervals based on duty cycle and storage patterns to protect against corrosion and fuel quality degradation in extreme climates.

GLL55B attachments & work tools

Grapples

The GLL55B is compatible with the GLL55B grapple model, which has a capacity of 55 cubic yards (1397 cubic meters). This attachment is designed for use with the 324D FM, 325D FM, and 330D FM mining shovel series.

Grapples

Orange Peel Grapples are available in the GSH15B and GSH20B models. The GSH15B has a capacity of 1.0 cubic yards (0.8 cubic meters) and a jaw opening of 104 inches (2642 millimeters), suitable for the 320D MH. The GSH20B has a capacity of 0.75 cubic yards (0.6 cubic meters) and a jaw opening of 80 inches (2000 millimeters), suitable for the 325D MH, 330D MH, M325D MH, and M325D L MH.

All GLL55B assemblies by section

Every catalogued assembly group for the Caterpillar GLL55B. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Frame And Body
270-9021 Cover Gp-Access
15***35Film-Warning; (Crush Hazard, Stay Back)2
15***36Film-Warning; (Read Operation Manual)2
27***21Cover Group-Access1
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Hydraulic System
270-9016 Cylinder & Lines Gp-Grapple
15***35Film-Warning; (Crush Hazard, Stay Back)2
15***36Film-Warning; (Read Operation Manual)2
27***16Cylinder & Lines Group-Grapple1
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216-4042 Cylinder Gp-Hydraulic -Grapple
21***42Cylinder Group-Hydraulic; -Grapple1
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305-8112 Manifold Gp-Rotator
30***12Manifold Group-Rotator, Rocker Lever Support1
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268-2792 Motor Gp-Gerotor
26***92Motor Group-Gerotor1
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270-7838 Rotator Gp-Hydraulic
27***38Rotator Group-Hydraulic1
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Service Equipment And Supplies
291-2638 Film Gp
29***38Film Group1
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291-2637 Film Gp
29***37Film Group1
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291-2639 Film Gp
29***39Film Group1
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Work Tool Arrangement
271-1533 Grapple Ar
13***34Plate-Identification; (Work Tool)1
26***31Crosshead As1
26***46Tong As-Grapple; -Female1
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271-1535 Grapple Ar
13***34Plate-Identification; (Work Tool)1
26***31Crosshead As1
26***48Tong As-Grapple; -Female1
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271-1534 Grapple Ar
13***34Plate-Identification; (Work Tool)1
26***31Crosshead As1
26***47Tong As-Grapple; -Female1
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Work Tools
270-9070 Fastener Gp-Grapple
09***73Bolt; (Socket Head) (M12x1.75x60mm)4
15***19Lockwasher8
25***30Spacer; (16.27x25.4x10.7-mm Thk)1
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270-9069 Pin Gp-Grapple
12***02Pin2
23***64Plate4
23***66Pin As2
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269-6546 Tong As-Grapple -Female
24***04Plate1
24***15Plate As2
26***46Tong As-Grapple; -Female1
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270-7840 Tong As-Grapple -Male
22***82Gear & Bearing As1
22***96Gear-Pinion; (13-Teeth)1
26***51Valve As-Relief; (1500-Psi)1
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270-7839 Tong As-Grapple -Male
27***07Kit-Seal; (Manifold)1
27***10Plate-Wear1
27***39Tong As-Grapple; -Male1
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269-6547 Tong As-Grapple -Female
21***42Cylinder Group-Hydraulic; -Grapple2
26***47Tong As-Grapple; -Female1
29***66Hose As4
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269-6548 Tong As-Grapple -Female
11***89Valve-Check (Po)1
15***11Lockwasher12
16***80Kit-Service; (Counterbalance Valve)1
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270-7841 Tong As-Grapple -Male
15***35Film-Warning; (Crush Hazard, Stay Back)2
15***36Film-Warning; (Read Operation Manual)2
27***41Tong As-Grapple; -Male1
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Frequently asked questions

What engine powers the compatible Cat machines for the GLL55B?

Compatible machines like the 324D FM, 325D FM, and 330D FM typically use Cat C7.1 ACERT or similar Tier 4 Final engines. Specific engine models vary by machine serial number and region.

What is the operating weight of the GLL55B?

Operating weight varies by configuration and attachment package. Consult the specific Operation and Maintenance Manual for the host machine to determine exact weight specifications for your setup.

What replaced the GLL55B?

The GLL55B is part of the GLL series forestry grapples. Successor models include the GLL60B and other updated Cat work tools designed for newer FM series machines. Check with your Cat dealer for the latest compatible attachments.

What GLL55B owners discuss

What engine powers the Caterpillar GLL55B, and what are the known powertrain or hydraulic behaviors for this series?
The Caterpillar GLL55B is powered by the Cat C7.1 ACERT engine. This powertrain provides optimum machine match for forestry applications. Hydraulic behaviors are tuned to support the specific duty cycles of the GLL series, with flow and pressure settings varying by configuration. Operators note that the hydraulic system is robust for grapple work but requires strict adherence to fluid specifications to prevent pump cavitation during high-load cycles. Variations in hydraulic performance exist depending on the specific machine configuration and serial range.
What undercarriage or wear patterns are typical for the GLL55B in forestry operations?
The GLL55B is a forest machine (FM) variant, equipped with specialized undercarriage components designed to resist damage from stumps, rocks, and debris common in logging environments. Wear patterns typically focus on track shoes, rollers, and idlers due to the abrasive nature of forest floor operations. The machine's design prioritizes durability over pure speed, resulting in undercarriage life heavily dependent on ground conditions and operator technique. Specific wear rates vary by configuration and operating environment.
Are there specific engine quirks or maintenance requirements for the Cat C7.1 ACERT series used in the GLL55B?
The Cat C7.1 ACERT engine requires precise fuel system maintenance to ensure optimal performance. Injector flow testing is critical to identify unbalanced fuel delivery that can cause rough operation, excessive emissions, or power loss. The engine is sensitive to fuel quality; water or microbial contamination in the fuel system can lead to hard starting, sputtering, or stalling under load. Regular inspection of fuel filters and water separators is necessary to prevent these issues. Engine performance and emissions compliance vary by configuration and regional emissions package.
What are common electrical or sensor issues reported for this machine type?
Electrical instability is a common concern in heavy construction and forestry equipment, including the GLL55B. Operators should monitor for symptoms such as slow or failed engine starts, flickering gauges, or intermittent power loss to critical systems. These issues often stem from weak or sulfated batteries, corroded terminals, or faulty alternator output. Faulty sensors can also cause rough idling or misfires. Ensuring all battery and ground connections are clean and properly torqued is essential for reliable operation. Electrical system behavior may vary by configuration and serial range.
What should be checked when buying a used Caterpillar GLL55B?
When purchasing a used GLL55B, verify the exact serial-prefix specification sheet to confirm the installed engine model, attachment package, and regional emissions configuration. Inspect the undercarriage for excessive wear on track shoes, rollers, and idlers, as forest machine configurations are subject to harsh conditions. Check the Cat C7.1 ACERT engine for signs of fuel system issues, such as injector leaks or rough idle, and verify the condition of the hydraulic system for leaks or cavitation damage. Confirm the history of fluid changes, ensuring that Cat DEO engine oil, Cat HYDO Advanced hydraulic oil, and Cat TDTO transmission fluid were used as specified. Cross-contamination of hydraulic fluids can cause sludge and valve blockage. Always consult official OEM service manuals for precise operating specs and safety protocols.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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