Can a Bobcat 642B Operate a Hydraulic Sweeper Attachment

[MikePhua]

The Bobcat 642B and Its Hydraulic Capabilities
The Bobcat 642B skid-steer loader was introduced in the early 1980s as part of Bobcat’s 600-series lineup, designed for light to medium-duty tasks in construction, agriculture, and property maintenance. With an operating weight of approximately 4,000 pounds and a rated operating capacity of around 1,200 pounds, the 642B was powered by an air-cooled gasoline engine—typically a Wisconsin VH4D or similar—delivering roughly 30 horsepower.
Bobcat, having pioneered the skid-steer concept in the late 1950s, had by the 1980s become a global leader in compact equipment. The 642B was one of the more popular models of its time, known for its simplicity, reliability, and ease of maintenance. However, its hydraulic system was relatively basic compared to modern machines, which raises questions about its ability to run high-demand attachments like hydraulic sweepers.
Hydraulic Flow and Pressure Limitations
The hydraulic system on the 642B delivers approximately 10–12 gallons per minute (GPM) at around 2,000 PSI. This is sufficient for basic attachments such as buckets, forks, and low-demand augers, but may fall short for continuous-flow tools like sweepers, trenchers, or brush cutters.
Hydraulic sweepers typically require:

• Flow rate: 12–20 GPM
  
• Pressure: 2,500–3,000 PSI
  
• Continuous duty cycle with cooling capacity
  

While the 642B can technically operate a sweeper, performance may be limited. The brush may rotate slowly, stall under load, or overheat the hydraulic fluid during extended use. Operators should monitor temperature and flow carefully, especially when sweeping heavy debris or working in hot climates.
Attachment Compatibility and Coupler Considerations
Most sweepers use standard quick couplers, but older machines like the 642B may have flat-face couplers or non-standard fittings. Adapters may be required to match the attachment’s hydraulic lines. Additionally, the auxiliary hydraulic circuit must be activated via a manual valve or foot pedal, depending on the machine’s configuration.
Operators should verify:

• Coupler type and size
  
• Flow direction and return path
  
• Case drain requirement (some sweepers need a third line)
  
• Mounting plate compatibility (standard Bob-Tach or modified)
  

If the sweeper includes a hydraulic angle function, the 642B may not have the auxiliary controls to operate it. In such cases, manual angle adjustment or a separate valve block may be necessary.
Field Experience and Operator Stories
A property manager in Ohio retrofitted his 642B with a used sweeper attachment to clean parking lots. While the brush rotated adequately on dry pavement, it struggled with wet leaves and gravel. After installing a flow control valve and upgrading the return filter, performance improved slightly, but the machine still overheated during long runs.
In contrast, a contractor in Alberta used a sweeper on a newer Bobcat S185 with 16 GPM flow and had no issues. He noted that older machines like the 642B are best suited for short bursts of sweeping or light-duty cleanup, not continuous commercial use.
Upgrade Options and Workarounds
To improve sweeper performance on a 642B:

• Install a hydraulic cooler to reduce fluid temperature
  
• Use a smaller-diameter brush to reduce torque demand
  
• Add a flow control valve to fine-tune output
  
• Replace couplers with flat-face quick-connects for better sealing
  
• Consider electric-over-hydraulic conversion for angle control
  

Alternatively, operators may choose a mechanical sweeper that mounts directly to the loader arms and uses ground contact for rotation. These units require no hydraulics and are ideal for gravel driveways or barn cleanup.
Maintenance and Safety Tips
When running a hydraulic sweeper:

• Check fluid levels before and after use
  
• Inspect hoses for wear and leaks
  
• Clean debris from the brush housing regularly
  
• Avoid sweeping uphill or into heavy piles
  
• Monitor engine RPM to maintain consistent hydraulic output
  

Operators should also wear eye protection and avoid standing near the discharge area, as sweepers can eject rocks and debris at high speed.
Conclusion
The Bobcat 642B can operate a hydraulic sweeper attachment, but with limitations. Its modest hydraulic flow and pressure may restrict performance, especially under heavy load or extended use. With careful setup, monitoring, and occasional upgrades, the 642B can handle light sweeping tasks effectively. For demanding commercial applications, newer machines with higher hydraulic capacity are better suited. Nonetheless, the 642B remains a durable and adaptable tool for property owners and small contractors seeking affordable versatility.