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What is the X337
The Bobcat X337 is a compact excavator in the sub-5-ton class — a useful machine for light-to-medium digging, general construction, landscaping or site work where maneuverability matters. Its operating weight is roughly 11,040 lbs. The X337 shares many components with other small excavators (undercarriage, tracks, attachments), making parts fairly accessible.
Because of its size and typical use, the hydraulic system — including swing motor and swivel joint — is critical: it drives the excavator’s ability to rotate the superstructure, swing the boom, and deliver hydraulic power to attachments.
What are Swing Motor and Hydraulic Swivel
Common Failures and Symptoms
Users of small excavators (like the X337) sometimes find that the swing motor or the swivel begins to leak — either hydraulic oil or grease — and may ultimately fail to function properly. Symptoms often reported:
Why These Issues Happen (Especially on Older or High-Hour Machines)
Several factors contribute to wear and failure of swing components:
When these components begin to leak or fail: swing becomes unreliable or impossible, meaning:
Replacing swing motor and swivel is not trivial:
Maintenance, Prevention and Best Practices
To avoid or postpone swing motor / swivel failures, operators should observe the following practices:
Consider a case of a small construction crew operating a well-worn X337 at a tight residential site. The operator noticed a slow, sticky swing when loading a trailer with debris. At first the swing would jerk when fully loaded; later, hydraulic oil pooled near the base, and eventually the swing function failed altogether.
Upon inspection, the swivel joint seal had worn and leaked hydraulic oil; internal bearing surfaces had partial scoring due to lack of lubrication after oil contamination. The operator ordered a replacement swing motor and swivel kit from a specialized supplier, then spent a weekend disassembling the house swivel, cleaning all mating surfaces, replacing seals, bearings, and re-torquing bolts per spec. After re-assembly and clean hydraulic fluid fill, the swing returned to smooth operation. This downtime cost two working days — but prevented a potential catastrophic failure (house drop or uncontrolled swing) under load.
Why Swing System Integrity Matters for Compact Excavators
Compact excavators such as the X337 rely heavily on hydraulic systems: boom, arm, bucket, swing, attachments — almost every movement depends on hydraulics. A failed swing motor or leaking swivel is not a minor inconvenience; it cripples the machine’s manoeuvrability and ability to operate attachments safely. In tight job sites or when using tilt buckets, grapples, or other attachments requiring precise rotation — swing reliability is critical for efficiency and safety.
What to Do When You Suspect Swing Motor or Swivel Trouble
Here’s a recommended checklist:
For compact excavators like the Bobcat X337, the swing motor and hydraulic swivel are vital components — they enable the machine to rotate its house, swing the boom/arm, and deliver hydraulic fluid to attachments while allowing full 360° rotation. Failure in this system often begins as leaks or slow swing, but can lead to complete swing loss, hydraulic contamination, or structural stress if ignored.
Because replacement often involves significant disassembly and correctly matched parts, maintenance discipline — clean fluid, regular inspection, using correct attachments — is the first line of defense. When treated properly, even an older machine can continue to perform reliably with smooth, safe swing performance. But pushing it beyond design limits, neglecting hydraulic maintenance, or ignoring early warning signs may lead to costly downtime — or worse, safety hazards.
The Bobcat X337 is a compact excavator in the sub-5-ton class — a useful machine for light-to-medium digging, general construction, landscaping or site work where maneuverability matters. Its operating weight is roughly 11,040 lbs. The X337 shares many components with other small excavators (undercarriage, tracks, attachments), making parts fairly accessible.
Because of its size and typical use, the hydraulic system — including swing motor and swivel joint — is critical: it drives the excavator’s ability to rotate the superstructure, swing the boom, and deliver hydraulic power to attachments.
What are Swing Motor and Hydraulic Swivel
- Swing Motor (Swing Drive Motor): a hydraulic motor responsible for rotating (slewing) the excavator’s upper structure (house) relative to the undercarriage, allowing the boom/arm to swing left or right. This motor converts hydraulic pressure and flow into rotational torque.
- Hydraulic Swivel (Swivel Joint / Rotary Joint): a mechanical/hydraulic coupling that allows hydraulic fluid to pass between the fixed undercarriage (tracks/base) and the rotating upper structure, while allowing 360° rotation without hose twisting.
Common Failures and Symptoms
Users of small excavators (like the X337) sometimes find that the swing motor or the swivel begins to leak — either hydraulic oil or grease — and may ultimately fail to function properly. Symptoms often reported:
- Hydraulic oil seeping or leaking around the swivel joint or swing motor housing
- Loss of swing ability, or jerky/unstable swing
- Slow or incomplete rotation under load
- Excessive noise or overheating during or after swing operation
Why These Issues Happen (Especially on Older or High-Hour Machines)
Several factors contribute to wear and failure of swing components:
- Hydraulic pressure and load cycles: Every time the machine swings under load (with bucket, arm extended, or with heavy material), the swing motor and swivel bear significant torque and pressure. Over time, seals, bearings and swivel passages degrade.
- Wear and contamination: Dirt, dust, moisture, or foreign particles can infiltrate hydraulic circuits; poor filtration or maintenance can accelerate wear of seals or internal components.
- Aging seals and components: Rubber seals, O-rings, bearings, and swivel seals dry out or wear with age — especially in machines used many hours or in harsh environments.
- Improper lifting/attachment use: Using heavy attachments, swinging under load, or sudden shock loads can stress the swing system more than it’s rated for, causing premature failure.
When these components begin to leak or fail: swing becomes unreliable or impossible, meaning:
- The excavator cannot rotate its house— limiting ability to dump, reposition, or operate attachments effectively
- Hydraulic fluid may contaminate tracks/base or leak out — environmental hazard and loss of oil
- If ignored, leakage can worsen: seals/gaskets may tear, bearings wear, internal hydraulic motor damage may occur
- Downtime needed for repair — sometimes extensive because accessing swing motor/swivel often involves disassembling hydraulics and possibly removing upper house assembly
Replacing swing motor and swivel is not trivial:
- Access can be difficult — often requires removing hydraulic hoses, control valves or even partial disassembly of the excavator’s superstructure to get to the swivel assembly and motor mount.
- Hydraulic control valve manifold maybe involved, depending on machine design — some wonder whether the “entire hydraulic control valve assembly” must be removed to extract the motor. For some small machines, that may be true to afford clearance.
- Replacement parts: aftermarket or reman hydraulic final drive / swing motors are available for X337, often sold as “complete hydraulic final drive motor” units — though they are final drive (travel motors), not swing motors. For swing-specific units, one must source components labeled “swing motor”, “swing drive assembly”, or “swivel joint for X337.”
Maintenance, Prevention and Best Practices
To avoid or postpone swing motor / swivel failures, operators should observe the following practices:
- Perform regular hydraulic maintenance: change hydraulic oil and filters according to schedule; use high-quality hydraulic fluid; monitor oil cleanliness and avoid contamination.
- Inspect seals, swivel joint and swing motor regularly: look for seepage, wetness around seals, or unusual grease/oil residue.
- Avoid swinging heavy loads while boom/arm is extended; minimize swing under maximum load or with attachments beyond rated weight.
- Use correct attachments compatible with machine capacity; avoid overly heavy buckets or tools that impose high moment loads.
- When replacing hydraulic components, insist on genuine or high-grade aftermarket parts; verify compatibility with X337 hydraulic pressure/flow specifications. The machine’s hydraulic components are part of what Bobcat considers “Powertrain + Hydraulics” coverage including swing motor, swivel, hydraulic valves, hoses, cylinders, pumps, etc.
- After maintenance or replacement, test swing at no-load and gradually with load; check for leaks, smoothness, and hydraulic pressure stability.
Consider a case of a small construction crew operating a well-worn X337 at a tight residential site. The operator noticed a slow, sticky swing when loading a trailer with debris. At first the swing would jerk when fully loaded; later, hydraulic oil pooled near the base, and eventually the swing function failed altogether.
Upon inspection, the swivel joint seal had worn and leaked hydraulic oil; internal bearing surfaces had partial scoring due to lack of lubrication after oil contamination. The operator ordered a replacement swing motor and swivel kit from a specialized supplier, then spent a weekend disassembling the house swivel, cleaning all mating surfaces, replacing seals, bearings, and re-torquing bolts per spec. After re-assembly and clean hydraulic fluid fill, the swing returned to smooth operation. This downtime cost two working days — but prevented a potential catastrophic failure (house drop or uncontrolled swing) under load.
Why Swing System Integrity Matters for Compact Excavators
Compact excavators such as the X337 rely heavily on hydraulic systems: boom, arm, bucket, swing, attachments — almost every movement depends on hydraulics. A failed swing motor or leaking swivel is not a minor inconvenience; it cripples the machine’s manoeuvrability and ability to operate attachments safely. In tight job sites or when using tilt buckets, grapples, or other attachments requiring precise rotation — swing reliability is critical for efficiency and safety.
What to Do When You Suspect Swing Motor or Swivel Trouble
Here’s a recommended checklist:
- Park on level ground, lower boom/arm, relieve hydraulic pressure.
- Inspect swivel joint base — look for oil or grease seepage.
- Listen for abnormal sounds when trying to swing (grinding, slipping).
- Check hydraulic fluid level and cleanliness — milky or contaminated fluid indicates seal failure.
- If leaks/symptoms present, schedule maintenance: order correct swing motor / swivel assembly parts; plan for partial disassembly (house rotation and counterweight removal may be needed).
- After replacement, flush hydraulic fluid and filters, bleed system if necessary, test carefully under light load first.
For compact excavators like the Bobcat X337, the swing motor and hydraulic swivel are vital components — they enable the machine to rotate its house, swing the boom/arm, and deliver hydraulic fluid to attachments while allowing full 360° rotation. Failure in this system often begins as leaks or slow swing, but can lead to complete swing loss, hydraulic contamination, or structural stress if ignored.
Because replacement often involves significant disassembly and correctly matched parts, maintenance discipline — clean fluid, regular inspection, using correct attachments — is the first line of defense. When treated properly, even an older machine can continue to perform reliably with smooth, safe swing performance. But pushing it beyond design limits, neglecting hydraulic maintenance, or ignoring early warning signs may lead to costly downtime — or worse, safety hazards.
