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The P&H 790TC and Its Historical Significance
The P&H 790TC truck crane, manufactured in 1967 by Harnischfeger Corporation (commonly known as P&H), represents a pivotal era in American crane engineering. Founded in 1884 in Milwaukee, Wisconsin, P&H was a dominant force in the development of lifting equipment throughout the 20th century. By the 1960s, their truck cranes were widely used in infrastructure projects, steel erection, and industrial plant construction.
The 790TC was part of a lineage that emphasized mechanical reliability, modular design, and field serviceability. With a lifting capacity in the 40–60 ton range depending on configuration, it featured a telescopic boom, hydraulic outriggers, and a robust drivetrain built to endure rough terrain and long hours. Thousands of units were sold across North America, and many were exported to Latin America, Southeast Asia, and the Middle East, where some remain in operation today.
Terminology Clarification
The specific issue with the 790TC in question involves the bell housing for a Fuller 1120 transmission. The part number 11209 has long been discontinued, and sourcing replacements has become increasingly difficult. This is a common problem with legacy equipment: as manufacturers evolve or merge, older components are phased out, leaving owners to rely on salvage, fabrication, or adaptation.
In this case, the bell housing serves as a critical interface between the engine and transmission. Without it, the powertrain cannot be assembled, rendering the crane inoperable. Given the age of the machine, even locating a donor unit is challenging, as most 790TCs have either been scrapped or heavily modified.
Strategies for Sourcing and Fabrication
Owners facing obsolete part issues have several avenues to explore:
In 2011, a crane operator in Alberta restored a 1965 P&H Omega crane for use in a rural bridge project. The original transmission had failed, and the bell housing was cracked. Unable to find a replacement, he partnered with a local college’s mechanical engineering department to fabricate a new housing using aluminum alloy. The project took six weeks and cost $4,000, but the crane was back in service and completed the job on schedule.
Similarly, in Brazil, a mining company repurposed a 790TC for lifting conveyor segments. When the transmission failed, they sourced a compatible housing from a retired logging truck and modified the mounts. Though not ideal, the solution extended the crane’s life by another five years.
Technical Considerations and Risks
When replacing or fabricating a bell housing, several parameters must be respected:
For those restoring or maintaining vintage cranes like the P&H 790TC:
The P&H 790TC is more than a relic—it’s a testament to mid-century American engineering. While parts like the Fuller 1120 bell housing may be obsolete, resourceful owners and skilled fabricators continue to breathe life into these machines. With careful planning, technical precision, and a bit of ingenuity, even a 1967 crane can return to service, lifting not just steel but the legacy of a bygone era.
The P&H 790TC truck crane, manufactured in 1967 by Harnischfeger Corporation (commonly known as P&H), represents a pivotal era in American crane engineering. Founded in 1884 in Milwaukee, Wisconsin, P&H was a dominant force in the development of lifting equipment throughout the 20th century. By the 1960s, their truck cranes were widely used in infrastructure projects, steel erection, and industrial plant construction.
The 790TC was part of a lineage that emphasized mechanical reliability, modular design, and field serviceability. With a lifting capacity in the 40–60 ton range depending on configuration, it featured a telescopic boom, hydraulic outriggers, and a robust drivetrain built to endure rough terrain and long hours. Thousands of units were sold across North America, and many were exported to Latin America, Southeast Asia, and the Middle East, where some remain in operation today.
Terminology Clarification
- Truck Crane: A mobile crane mounted on a truck chassis, allowing for highway travel and on-site lifting.
- Bell Housing: A cast metal component that connects the engine to the transmission, enclosing the flywheel and clutch assembly.
- Fuller Transmission: A line of heavy-duty manual transmissions produced by Eaton Corporation, widely used in commercial vehicles and industrial equipment.
The specific issue with the 790TC in question involves the bell housing for a Fuller 1120 transmission. The part number 11209 has long been discontinued, and sourcing replacements has become increasingly difficult. This is a common problem with legacy equipment: as manufacturers evolve or merge, older components are phased out, leaving owners to rely on salvage, fabrication, or adaptation.
In this case, the bell housing serves as a critical interface between the engine and transmission. Without it, the powertrain cannot be assembled, rendering the crane inoperable. Given the age of the machine, even locating a donor unit is challenging, as most 790TCs have either been scrapped or heavily modified.
Strategies for Sourcing and Fabrication
Owners facing obsolete part issues have several avenues to explore:
- Salvage Yards and Equipment Brokers: Specialized dealers in vintage construction equipment may have access to retired units or parts inventories. Networking within restoration communities often yields leads.
- Custom Fabrication: Machine shops with CNC capabilities can reverse-engineer a bell housing using original dimensions or surviving samples. This approach requires precision, as misalignment can cause drivetrain failure.
- Adaptation from Similar Models: Some later-model Fuller transmissions share bolt patterns or clutch dimensions. With careful modification, a housing from a 1250 or 1350 series may be adapted.
- Casting Reproduction: Foundries can reproduce cast iron components using sand molds, though this is costly and requires detailed drawings or 3D scans.
In 2011, a crane operator in Alberta restored a 1965 P&H Omega crane for use in a rural bridge project. The original transmission had failed, and the bell housing was cracked. Unable to find a replacement, he partnered with a local college’s mechanical engineering department to fabricate a new housing using aluminum alloy. The project took six weeks and cost $4,000, but the crane was back in service and completed the job on schedule.
Similarly, in Brazil, a mining company repurposed a 790TC for lifting conveyor segments. When the transmission failed, they sourced a compatible housing from a retired logging truck and modified the mounts. Though not ideal, the solution extended the crane’s life by another five years.
Technical Considerations and Risks
When replacing or fabricating a bell housing, several parameters must be respected:
- Alignment Tolerance: The crankshaft and input shaft must align within 0.005 inches to prevent bearing wear.
- Material Strength: Cast iron is preferred for its vibration damping, but aluminum may be used with reinforcement.
- Bolt Pattern Accuracy: Mismatched bolt holes can lead to stress fractures or mounting failure.
- Clutch Clearance: The housing must accommodate the clutch assembly without interference.
- Premature transmission wear
- Vibration and noise
- Clutch engagement issues
- Safety hazards during operation
For those restoring or maintaining vintage cranes like the P&H 790TC:
- Document all dimensions before disassembly
- Consult transmission manuals and cross-reference part numbers
- Join vintage equipment forums and restoration groups for leads
- Consider hybrid solutions using modern components with adapter plates
- Budget for delays and unexpected fabrication challenges
The P&H 790TC is more than a relic—it’s a testament to mid-century American engineering. While parts like the Fuller 1120 bell housing may be obsolete, resourceful owners and skilled fabricators continue to breathe life into these machines. With careful planning, technical precision, and a bit of ingenuity, even a 1967 crane can return to service, lifting not just steel but the legacy of a bygone era.
