633D Caterpillar 633D Specifications & Technical Data (1975—2026)

Reliability and durability

that's what you get from the 450 flywheel horsepower Cat Model 3408 diesel, a 65° V-8 with 1,099 cu. in. (18.0 liters) displacement. Turbocharged and jacket water aftercooled for efficient fuel combustion, the 3408 offers performance with serviceability, long component life, simplified rebuild procedures.

Large capacity

coupled with low weight-to-horsepower . . . add up to excellent loadability, maximum loads and high productivity. And you get these time-proven features: powerful double-acting hydraulics and cantilever-mounted wheels.

Cushion hitch

provides smoother hauling and higher usable speeds. It connects two separate tractor and scraper castings at the top and bottom by mechanical links, forming a pivoting parallelogram arrangement which allows vertical movement between the two sections. A hydraulic cylinder connects the links from the bottom tractor pivot to the top scraper pivot. When the 633D hits a bump, the load cylinder forces oil into two nitrogen-over-oil accumulators. The accumulators cushion the bump like a shock absorber. The system can handle several shocks at the same time to reduce machine bounce. This means greater productivity, longer machine life, reduced haul road maintenance, and less operator fatigue.

Transmission

Caterpillar 8-speed semiautomatic transmission with variable capacity torque converter and two special loading ranges (in addition to the standard 1st and 2nd gears). Loading: Operator chooses standard 1st or 2nd gear for average materials, load range 1 for short distance loading or load range 2 for wet, poor traction materials. Travel: All shifts up or down from 2nd to the gear selected are automatic. Upshifting is limited to the speed selected by control lever. Reverse, 1st and 2nd are manually selected. A foot control holds transmission in any gear. Standard downshift inhibitor helps prevent engine overspeed due to improper downshifts. Variable capacity torque converter makes maximum horsepower available to the hydraulic system for loading and limits rim pull to prevent wheel slip or to allow short-distance loading.

Cat 8-speed semiautomatic transmission

combines automatic shifting with high torque multiplication and direct drive mechanical efficiency. Reverse, 1st, 2nd and the highest desired gear are manually selected. The transmission shifts up and down automatically between 2nd and the highest selected gear. Reverse and gears 1 and 2 are torque converter drive for powerful rimpull needed for loading and dumping. Gears 3 through 8 are direct drive for quick acceleration and high travel speeds. A hydraulic modulator monitors ground speed to control shifting between 2nd and the highest selected gear, reducing the possibility of lugging and overspeed. Downshift inhibitor, which helps prevent engine overspeed in too-rapid downshifts, is standard.

steering

Two double-acting hydraulic cylinders. Hydraulic follow-up system for automotive feel. Positive, wellmodulated oil flow control for constant steering response. Full 90° right or left, unrestricted by ROPS. Width required for curb-to-curb turn . . . 40'7" (12.4 m).

brakes

(System meets OSHA regulations.) Air-actuated, cam-operated, expanding-shoe type (sequenced to brake scraper first). Air-actuated emergency braking system and spring-actuated, oil pressure-disengaged parking brake system are standard. Optional hydraulic retarder.

Machine and operator protection

have been designed into the 633D: Integral ROPS canopy, vibration isolated for improved sound suppression, standard on machines sold in U.S.A. Oil-disc parking brake . . . separate from the emergency braking system. Emergency braking system designed so that no failure of a single component on the line will cause a total loss of brakes. Automatically actuates if operator fails to engage after warning horn sounds. Seat belt, windshield wiper are standard. Ground-driven supplemental steering system . . . supplies hydraulic pressure for steering if engine stops. ROPS sound-suppressed cab. Back-up alarm.

Controls

Three levers for hydraulic actuation. Elevator . . . two speeds forward, one reverse. Bowl . . . raise, hold, lower. Ejection . . . dump, hold, return. Detent held with automatic kickout on dump and return. Dump position may be held to override kickout.

Convenient Controls

are designed to improve operator efficiency: Ejector positions are detent-held, with automatic kickout on dump and return, to free operator's hand for other controls. Throttle lock (optional) holds throttle in high idle position during long hauls or when climbing grades. Emergency brake button control located on dash. Familiar location of transmission console and scraper controls at operator's right.