Mechanical Functions & Shifting of a 1984 International S1700 Dump Truck

The bucket kickout system on the CAT 924G wheel loader is designed to automate the stopping points of the bucket during lift, dump, and return-to-dig operations. This system enhances operator efficiency and reduces wear on hydraulic components by preventing over-travel. It relies on a combination of joystick-mounted magnets, electrical sensors, and programmable logic within the machine’s control module.

When functioning properly, the joystick “latches” into preset positions, allowing the operator to engage automatic movements. These positions are governed by magnetic sensors and electrical signals routed through an 8-wire connector beneath the joystick assembly.

Basic Truck Overview

• The International S-series (including S1700) was produced by International Harvester (later Navistar) starting around 1978 and spanning into the 1980s. It was a medium-duty conventional truck used in many vocational applications, including dump trucks. Specifications (engines, axle ratings, etc.) varied by configuration.
• A 1984 International S1700 dump truck would often have a manual transmission, possibly a 5-speed with a two-speed rear axle (“dual-range” rear axle), and a diesel engine (though older S1700s may have had gasoline engines, depending on region and configuration).

Transmission & Two-Speed Axle Function

One of the main mechanical peculiarities discussed by owners involves how to shift when the truck has a two-speed rear axle (a dual-range axle), plus a regular multi-speed transmission (e.g. 5-speed).

Here’s how it works in practice:

• The two-speed axle has a knob or lever (in this case a red knob on the shift lever) that controls switching the rear axle between Low Range and High Range.
• To travel through all “10 speeds” (i.e. each of the 5 main gears times either low or high rear axle range), the driver shifts both the main transmission and the axle range.

Typical shift sequence from standstill:

• First gear, rear axle low (“1st low”)
• Shift main transmission to first in high axle range (“1st high”) without shifting gears, by pulling up the knob on the shift lever
• Then second gear low, second gear high, and so on.

Some specifics:

• The knob pushed down = low axle range
• The knob pulled up = high axle range
• When going from low range to high range in the same gear, some drivers use just the throttle pedal (lifting up), others use clutch plus giving throttle, depending on the load and whether you want to ease the mechanical stress.

Advice from more experienced operators suggests using the clutch when first getting used to the truck, especially for shifting rear axle range under load, so as to reduce wear on the axle gears. After familiarity, some drivers rely more on lifting the throttle gear-lever technique (pedal shift).

Other Mechanical / Auxiliary Functions

From user conversation:

• There is a device suspected to be a trailer brake controller mounted somewhere (in cab or on chassis). It has many wires, a handle, and a steel line; the steel line likely connects to the truck hydraulic brake system. The handle allows the operator to manually apply trailer brakes without using the truck’s service brakes.
• Power steering cylinder leaks are reported in some S1700 / related models. Owners note that parts availability for older S-series trucks may be limited, especially for gas engines or less common configurations.

Terminology & Key Components Defined

• Dual-range rear axle: a rear axle that has two selectable ratio ranges (Low / High). Enables more gear ratios by switching the rear axle gearing, allowing more engine speed flexibility without shifting the main transmission.
• Knob / lever for axle range: control mounted on the shift lever (or near shifter) to switch between low and high rear axle ratio.
• Pedal shift vs clutch shift:
   • Pedal shift = lifting / adjusting throttle or easing load without using the clutch to shift axle range.
   • Clutch shift = disengaging main transmission via clutch before shifting rear axle range, to reduce stress.
• Trailer brake controller (auxiliary brakes): a device that allows independent control of trailer brakes, often proportionally tied to the pressure on the truck’s brakes, or manually via a handle.
• Service brakes vs auxiliary brakes: service brakes are the vehicle’s primary braking system; auxiliary brakes are additional braking systems, e.g. trailer brakes, engine brakes, etc.

Real Life Examples & Experience

• One owner asked for clarification: when shifting from “1st Low” to “1st High” (i.e. same first gear but switching rear axle range), do they need to use clutch, or can throttle alone suffice. Feedback suggested clutch is safer, but with experience and light load, throttle-based shifting is used by many.
• Another case: The brake controller device—one owner thought it mechanical (steel line) but others pointed out wires attach, so it's electric/hydraulic mixed. The handle allows applying trailer brakes while truck is stationary or moving, helpful when towing loads.
• Regarding parts: owners of older S1700s mention that locating parts for the power steering, hydraulic cylinders, and unique knobs / linkage for the dual-range rear axle are more difficult compared to more modern trucks. Specialty shops or used parts scavenged from similar trucks tend to fill gaps.

Common Issues, Troubleshooting & Maintenance Tips

• The dual-range axle linkage (the knob and internal mechanism) can wear, misalign, or develop delay in shifting; proper lubrication, periodic inspection of linkage and cabling is important.
• Using the clutch when shifting to high range, particularly under load, helps prevent damage to gears in rear axle.
• Trailer brake controller needs correct wiring and mechanical connections; if noisy or dragging, adjusting and inspecting steel lines / return lines / connectors can prevent binding or overheating.
• Power steering leak issues: check cylinder seals, hoses, hose clamps; replacement of seals usually possible but may need matching dimensions carefully.
• For older trucks, ensure that springs / shocks / suspension components are in good shape; wear may increase loads on drivetrain and complicate smooth shifting.

Useful Advice Before Operating or Restoring One

• Familiarize with exact configuration: is the rear axle dual-range? What is the main transmission (how many speeds)? Know the engine make & type.
• Test shifting both clutch & throttle methods in low gear under light load to see response.
• Check for availability of parts like the range shift knob components, trailer brake controller, power steering cylinders.
• Document the condition of mechanical linkages, wiring, hydraulic lines before starting repairs or restoration.

Conclusion: Precision Requires Cleanliness

The CAT 924G’s kickout system exemplifies the delicate interplay between mechanical components and electronic control. While robust in design, it remains vulnerable to environmental contamination—especially during restoration or repair. Diagnosing such issues demands not only electrical expertise but also an understanding of magnetic field behavior and sensor calibration.

In the world of heavy equipment, the smallest particles can cause the biggest problems. Whether it’s metal shavings from a grinder or salt dust from winter roads, vigilance in cleanliness and diagnostic rigor ensures that automation features like kickout systems continue to serve their purpose: making hard work just a little easier.