10-11-2025, 06:12 PM
The short red-handled knob located near the battery shutoff on the 1976 International Harvester 175C track loader is most likely the manual fuel shutoff or emergency engine stop. This mechanical control is designed to cut fuel delivery in case of electrical failure or for maintenance purposes.
Machine Background and Fuel System Design
The IH 175C was part of International Harvester’s mid-1970s lineup of crawler loaders, built for rugged earthmoving, demolition, and site prep. Powered by a DT-466 diesel engine, the 175C featured mechanical fuel injection, hydraulic loader controls, and a robust undercarriage suited for heavy-duty work. The DT-466 engine itself was a 7.6-liter inline-six, widely used in agricultural and industrial applications, known for its torque and reliability.
Unlike modern electronically governed engines, the DT-466 relied on a mechanical injection pump, typically a Bosch or Roosa Master unit. These pumps included a manual shutoff lever that could be actuated by a cable or rod—often routed to a red knob in the operator’s vicinity. This knob provided a direct mechanical link to the fuel rack, allowing the operator to stop the engine without relying on electrical solenoids.
Terminology and Component Overview
The red knob serves as a backup engine stop in several scenarios:
Field Anecdotes and Practical Advice
A contractor in Montana reported that his 175C wouldn’t shut down with the key. After tracing the wiring, he found the solenoid had failed. Fortunately, the red knob near the battery box allowed him to stop the engine manually. He later replaced the solenoid but kept the knob functional as a backup.
Another operator in Georgia used the knob during winter starts. After preheating the engine block, he would pull the knob to prime the system, then push it in just before cranking. This helped prevent overfueling and reduced white smoke on cold mornings.
Maintenance and Inspection Tips
The red-handled knob on the IH 175C is a simple but vital control, offering manual fuel shutoff for safety, service, and reliability. In an era before electronic diagnostics, such mechanical backups were essential. With proper care and understanding, this knob remains a functional part of the machine’s legacy—proof that sometimes, the simplest solutions endure the longest.
Machine Background and Fuel System Design
The IH 175C was part of International Harvester’s mid-1970s lineup of crawler loaders, built for rugged earthmoving, demolition, and site prep. Powered by a DT-466 diesel engine, the 175C featured mechanical fuel injection, hydraulic loader controls, and a robust undercarriage suited for heavy-duty work. The DT-466 engine itself was a 7.6-liter inline-six, widely used in agricultural and industrial applications, known for its torque and reliability.
Unlike modern electronically governed engines, the DT-466 relied on a mechanical injection pump, typically a Bosch or Roosa Master unit. These pumps included a manual shutoff lever that could be actuated by a cable or rod—often routed to a red knob in the operator’s vicinity. This knob provided a direct mechanical link to the fuel rack, allowing the operator to stop the engine without relying on electrical solenoids.
Terminology and Component Overview
- Fuel Shutoff Lever: A mechanical arm on the injection pump that cuts fuel flow when pulled.
- Battery Disconnect Switch: A rotary or lever-style switch that isolates the battery from the electrical system.
- Emergency Stop Cable: A steel cable connected to the shutoff lever, often terminating in a red knob for visibility.
- Injection Pump Rack: The internal mechanism that meters fuel delivery. Moving the rack to the “off” position stops injection.
The red knob serves as a backup engine stop in several scenarios:
- Electrical failure: If the key switch or solenoid fails, the knob allows manual shutdown.
- Maintenance: Mechanics can stop the engine during service without climbing into the cab.
- Safety: In case of runaway or uncontrolled operation, the knob provides immediate fuel cutoff.
Field Anecdotes and Practical Advice
A contractor in Montana reported that his 175C wouldn’t shut down with the key. After tracing the wiring, he found the solenoid had failed. Fortunately, the red knob near the battery box allowed him to stop the engine manually. He later replaced the solenoid but kept the knob functional as a backup.
Another operator in Georgia used the knob during winter starts. After preheating the engine block, he would pull the knob to prime the system, then push it in just before cranking. This helped prevent overfueling and reduced white smoke on cold mornings.
Maintenance and Inspection Tips
- Lubricate the cable monthly with light oil to prevent binding.
- Check the knob’s mounting bracket for corrosion or looseness.
- Test the shutoff function quarterly by pulling the knob with the engine running.
- Inspect the cable sheath for cracks or wear, especially near bends or firewall pass-throughs.
- Ensure the knob is clearly labeled to avoid confusion with other controls.
The red-handled knob on the IH 175C is a simple but vital control, offering manual fuel shutoff for safety, service, and reliability. In an era before electronic diagnostics, such mechanical backups were essential. With proper care and understanding, this knob remains a functional part of the machine’s legacy—proof that sometimes, the simplest solutions endure the longest.
