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The KH Series and Its Mechanical Legacy
Kubota’s KH series excavators, including models like the KH-60, KH-91, and KH-151, were compact hydraulic machines produced during the 1980s and early 1990s. These excavators were designed for small contractors, farmers, and municipalities needing reliable digging power in tight spaces. The KH-60, for example, featured a 3-cylinder Kubota diesel engine producing around 20 horsepower, with an operating weight near 2,800 kg. Its mechanical simplicity and fuel efficiency made it a favorite in rural markets across Asia and North America.
Kubota, founded in 1890 in Osaka, Japan, began producing construction equipment in the 1970s. By the time the KH series was introduced, Kubota had already established a reputation for durable engines and compact design. The KH series sold tens of thousands of units globally, with many still in operation today.
Linkage Controls and Operator Fatigue
One of the defining features of early KH excavators is their linkage-type control system. These mechanical levers, often mounted in front of the operator, use rods and pivots to actuate hydraulic valves directly. While robust and easy to maintain, they can be physically demanding. Operators frequently report knee strain and limited ergonomic flexibility, especially during long shifts.
In contrast, modern excavators use pilot controls—low-pressure hydraulic joysticks that send signals to the main valve block. These systems reduce operator fatigue and allow for smoother, more precise movements. Some newer models even offer electronic controls with programmable patterns and fingertip sensitivity.
Is Conversion to Joystick Controls Feasible
Upgrading a KH series machine from linkage controls to joystick-style push-pull cables or pilot hydraulics is technically possible but comes with trade-offs.
Can a Two-Speed Travel Motor Be Added
The KH series typically features a single-speed travel motor, limiting mobility on large job sites. Adding a two-speed motor is theoretically possible but requires:
Terminology Notes
Kubota’s KH series remains a testament to mechanical durability, but its control systems reflect an era before operator ergonomics became standard. While upgrades are possible, they require careful planning and may not always justify the investment. For owners committed to keeping these machines running, small modifications like control relocation can make a big difference in daily usability. For those seeking modern features, transitioning to newer Kubota models may offer better long-term value.
Kubota’s KH series excavators, including models like the KH-60, KH-91, and KH-151, were compact hydraulic machines produced during the 1980s and early 1990s. These excavators were designed for small contractors, farmers, and municipalities needing reliable digging power in tight spaces. The KH-60, for example, featured a 3-cylinder Kubota diesel engine producing around 20 horsepower, with an operating weight near 2,800 kg. Its mechanical simplicity and fuel efficiency made it a favorite in rural markets across Asia and North America.
Kubota, founded in 1890 in Osaka, Japan, began producing construction equipment in the 1970s. By the time the KH series was introduced, Kubota had already established a reputation for durable engines and compact design. The KH series sold tens of thousands of units globally, with many still in operation today.
Linkage Controls and Operator Fatigue
One of the defining features of early KH excavators is their linkage-type control system. These mechanical levers, often mounted in front of the operator, use rods and pivots to actuate hydraulic valves directly. While robust and easy to maintain, they can be physically demanding. Operators frequently report knee strain and limited ergonomic flexibility, especially during long shifts.
In contrast, modern excavators use pilot controls—low-pressure hydraulic joysticks that send signals to the main valve block. These systems reduce operator fatigue and allow for smoother, more precise movements. Some newer models even offer electronic controls with programmable patterns and fingertip sensitivity.
Is Conversion to Joystick Controls Feasible
Upgrading a KH series machine from linkage controls to joystick-style push-pull cables or pilot hydraulics is technically possible but comes with trade-offs.
- Push-Pull Cable Joysticks: These mimic pilot controls but remain mechanical. They relocate the control levers beside the seat, improving ergonomics. Installation requires custom brackets, cable routing, and linkage adaptation to the valve block.
- Pilot Hydraulic Conversion: This involves installing pilot valves, hoses, and a dedicated pilot pump. It offers the smoothest control but is expensive and complex. Most KH machines lack the hydraulic infrastructure to support this without major modification.
- Electronic Retrofit: Rarely attempted due to cost and compatibility issues. Requires sensors, actuators, and a control module—often exceeding the value of the machine.
Can a Two-Speed Travel Motor Be Added
The KH series typically features a single-speed travel motor, limiting mobility on large job sites. Adding a two-speed motor is theoretically possible but requires:
- Matching Motor Dimensions: The new motor must fit the existing frame and sprocket mount.
- Hydraulic Flow Compatibility: Two-speed motors demand higher flow rates. The KH’s pump may need upgrading.
- Control Integration: A switch or lever must be added to toggle speeds, along with plumbing changes.
Terminology Notes
- Linkage Controls: Mechanical levers connected by rods to hydraulic valves.
- Pilot Controls: Low-pressure hydraulic joysticks that actuate valves indirectly.
- Travel Motor: Hydraulic motor that drives the tracks or wheels of an excavator.
- If comfort is a priority, consider push-pull cable conversion for control relocation.
- For performance upgrades like two-speed travel, weigh the cost against replacing the machine.
- Maintain original controls if reliability and simplicity are more valuable than comfort.
Kubota’s KH series remains a testament to mechanical durability, but its control systems reflect an era before operator ergonomics became standard. While upgrades are possible, they require careful planning and may not always justify the investment. For owners committed to keeping these machines running, small modifications like control relocation can make a big difference in daily usability. For those seeking modern features, transitioning to newer Kubota models may offer better long-term value.
