10-18-2025, 02:14 PM
The National 800B and Its Historical Role
The National 800B truck-mounted crane, introduced in the mid-1980s by National Crane Corporation, was designed to meet the growing demand for mobile lifting solutions in utility, construction, and oilfield operations. National Crane, founded in Nebraska in 1947, became a leading manufacturer of boom trucks and hydraulic cranes, later acquired by Manitowoc in 2002. The 800B model featured a telescoping boom with multiple hydraulic functions, mounted on a commercial truck chassis for road mobility and rapid deployment.
With a lifting capacity of approximately 23 tons and boom lengths ranging from 60 to 100 feet depending on configuration, the 800B was widely adopted across North America. Its modular design and mechanical simplicity made it a favorite among fleet operators and independent riggers.
Terminology Notes
Servicing the extension cylinder on a National 800B is a multi-step process that requires partial disassembly of the boom. The base section remains mounted to the crane, while the remaining boom sections—typically three—must be removed as a cartridge. This allows access to the internal components, including:
Challenges and Practical Advice
One operator in Connecticut recalled pulling the cartridge assembly with a gantry crane and laying it across sawhorses for inspection. He emphasized labeling each cable and hose to avoid confusion during reinstallation. Another technician in New York noted that aligning the boom sections during reassembly took longer than the actual seal replacement.
A rigger in Alberta shared that he used a 40-foot shop bay with overhead hoist to handle the cylinder. He recommended using a long steel pipe to guide the cylinder out evenly and prevent scoring the bore.
Preventive Measures and Recommendations
Servicing the extension cylinder on a 1987 National 800B is a labor-intensive but manageable task. With proper planning, workspace, and attention to detail, operators can restore full boom functionality and extend the life of this classic truck-mounted crane. The 800B’s enduring presence in fleets across North America is a testament to its design—and to the riggers who keep it running.
The National 800B truck-mounted crane, introduced in the mid-1980s by National Crane Corporation, was designed to meet the growing demand for mobile lifting solutions in utility, construction, and oilfield operations. National Crane, founded in Nebraska in 1947, became a leading manufacturer of boom trucks and hydraulic cranes, later acquired by Manitowoc in 2002. The 800B model featured a telescoping boom with multiple hydraulic functions, mounted on a commercial truck chassis for road mobility and rapid deployment.
With a lifting capacity of approximately 23 tons and boom lengths ranging from 60 to 100 feet depending on configuration, the 800B was widely adopted across North America. Its modular design and mechanical simplicity made it a favorite among fleet operators and independent riggers.
Terminology Notes
- Extension Cylinder: A hydraulic actuator inside the boom that controls the telescoping sections.
- Crowd Cable: A cable system that assists in boom extension and retraction, often routed through internal sheaves.
- Cartridge Assembly: The nested boom sections that slide within each other, housing the extension cylinder and cable systems.
- Wear Pads: Polymer or composite pads that reduce friction between boom sections and prevent metal-on-metal contact.
Servicing the extension cylinder on a National 800B is a multi-step process that requires partial disassembly of the boom. The base section remains mounted to the crane, while the remaining boom sections—typically three—must be removed as a cartridge. This allows access to the internal components, including:
- Extension cylinder
- Crowd cables
- Internal sheave bearings
- Wear pads
Challenges and Practical Advice
- Cylinder Length: A typical 18-foot extension cylinder becomes 36 feet when fully disassembled. Ensure adequate workspace for extraction and reassembly.
- Alignment Complexity: Reinstalling the boom sections and aligning cables and sheaves requires precision. Misalignment can cause binding or premature wear.
- Inspection Opportunity: While the boom is apart, inspect all internal components. Replace worn wear pads, check sheave bearings for play, and verify cable integrity.
- Seal Replacement: Repacking the cylinder is straightforward once removed. Use OEM seal kits and verify rod surface condition before reassembly.
One operator in Connecticut recalled pulling the cartridge assembly with a gantry crane and laying it across sawhorses for inspection. He emphasized labeling each cable and hose to avoid confusion during reinstallation. Another technician in New York noted that aligning the boom sections during reassembly took longer than the actual seal replacement.
A rigger in Alberta shared that he used a 40-foot shop bay with overhead hoist to handle the cylinder. He recommended using a long steel pipe to guide the cylinder out evenly and prevent scoring the bore.
Preventive Measures and Recommendations
- Schedule Service During Off-Season: Boom disassembly can take several days. Plan around downtime to avoid disrupting operations.
- Use Proper Lifting Equipment: Boom sections are heavy and awkward. Use slings, spreader bars, and hoists rated for the load.
- Document Cable Routing: Take photos before disassembly to aid in reassembly.
- Replace All Wear Items: Don’t reuse old pads or seals. Preventative replacement reduces future labor costs.
- Pressure Test After Reassembly: Verify cylinder integrity and hose connections before returning to service.
Servicing the extension cylinder on a 1987 National 800B is a labor-intensive but manageable task. With proper planning, workspace, and attention to detail, operators can restore full boom functionality and extend the life of this classic truck-mounted crane. The 800B’s enduring presence in fleets across North America is a testament to its design—and to the riggers who keep it running.
