Cat D6R Series II: power ratings, steering arrangements and blade choices

Series II engine power: the old columns mix rating conventions

The C9-powered D6R Series II brochure AEHQ5437 separates the standard tractor from the XL, XW and LGP arrangements. The standard machine has the lower flywheel rating; the other chassis share the higher one. Gross output is a different row.

Figures previously labelled 165 or 185 gross horsepower match the brochure's flywheel outputs, so a comparison using those labels would understate the published gross ratings. The earlier entries remain visible alongside the corrected measurement basis.

Equipment explains another apparent contradiction. Cat gives the XL separate operating weights for Finger Tip Control and differential steering. The 41914 lb figure belongs to differential steering, while the lighter FTC arrangement is listed separately.

Shipping weight uses a partly filled fuel tank and excludes the operating blade arrangement. Neither should be substituted for a trailer's actual loaded weight.

Differential steering is a hardware choice

On the FTC version, steering clutches and brakes control the turn. The alternative differential system speeds one track while slowing the other, maintaining drive to both. Its tiller also selects travel direction and carries shift buttons.

Inspect the controls and fitted components before ordering steering parts: the same D6R II badge covers both arrangements.

The transmission's automatic functions also differ from one another. Auto-shift selects a chosen forward/reverse pairing for repeated direction changes. Auto-kickdown responds to increased load by selecting a lower gear.

A machine changing gear under load is not necessarily failing to hold the operator's selected directional pairing. Cat's diagnostic connector provides access to stored information through its service equipment, and the brochure identifies pressure test points for hydraulic and powertrain diagnosis.

Match the blade to the undercarriage and rear equipment

The PAT blade is offered on differential-steer XL, XW and LGP machines and requires a rear work-tool attachment. Cat does not recommend that arrangement for large-rock or stump work. A six-way blade advertised on a used dozer therefore needs its rear equipment and steering arrangement checked, not just a photograph showing the blade angled.

XL extends track support forward to improve balance and grading control. XW adds gauge and shoe width for wetter ground. LGP combines wide shoes, a longer roller frame and broader gauge for soft, spongy conditions.

These are purposeful chassis differences; fitting wider shoes does not recreate every LGP component. The SU, straight and angle blades have separate capacities and positions relative to the tractor, so blade volume alone cannot select the right configuration.

The AMOCS radiator uses separate cooling modules and a two-pass coolant path. One damaged core can be serviced without replacing the whole radiator assembly. An optional protective grid is intended for abrasive airborne debris.

On a machine with a history of hot running, the cooler arrangement and protective equipment deserve inspection before assuming the engine rating is the cause.

Cat D6R Series II, AEHQ5437, August 2002: engine, steering, blades, undercarriage and specification conditions