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621 Partial Wheel Tractor-Scraper

Tractor Engine

Cat® C13

Flywheel Power - Tractor

407 HP

Top Speed - Loaded

33.5 mile/h


Caterpillar offers partial wheel tractor-scraper power units designed for specialty machines that complement the traditional Cat® product line. These tractor-only configurations are available for purchase directly from Caterpillar OEM Solutions. They can be leveraged for a variety of final machines, including water pulls, elevating scrapers, lowboy trailer power units, and more. With improvements in productivity combined with enhancements in operator comfort and new safety features – Powered Access System and effective wet disc brakes – this machine offers high returns on time and investment.


360° View


360° Exterior view. Double click on the image to zoom in on any area of the product.


  • Engine
    Spec Value
    Tractor Engine Cat® C13
    Flywheel Power - Tractor 407 HP
    Note Meets U.S. EPA Tier 4 Final or EU Stage V emission standards, or equivalent to U.S. EPA Tier 2, or equivalent to U.S. EPA Tier 3 and EU Stage IIIA.
  • Transmission
    Spec Value
    Top Speed - Loaded 33.5 mile/h
    1 Forward 3.1 mile/h
    2 Forward 5.5 mile/h
    3 Forward 7.5 mile/h
    4 Forward 10.1 mile/h
    5 Forward 13.6 mile/h
    6 Forward 18.4 mile/h
    7 Forward 24.8 mile/h
    8 Forward 33.5 mile/h
    Reverse 5.7 mile/h
  • Steering
    Spec Value
    Width - 180° Turn 38.6 ft
  • Standards
    Spec Value
    Brakes ISO 3450:2011
    ROPS/FOPS ROPS: ISO 3471:2008 for up to 17 084 kg (37,664 lb). FOPS: ISO 3449:2005 Level II.
    Cab Seat Belt: SAE J386:JUN1985
  • Service Refill Capacities - Tractor
    Spec Value
    Fuel Tank 216.1 gal (US)
    Crankcase 9.7 gal (US)
    Transmission 25.5 gal (US)
    Differential 41.7 gal (US)
    Final Drive - Each 5 gal (US)
    Cooling System 11 gal (US)
    Hydraulic Reservoir 21.9 gal (US)
    Windshield Washer 1.3 gal (US)

Standard Equipment


  • Standard and optional equipment may vary. Consult your Cat dealer for details.


  • Cat® C13 engine with Mechanically Actuated Electronic Unit Injection (MEUI™)
  • Transmission: 8-speed planetary powershift, ECPC control, APECS software, programmable top gear selection, transmission hold, differential lock, guard - power train, ground speed control, machine speed limit
  • Cat engine brake
  • Electric start, 24V
  • Fan, hydraulic
  • Ground level engine shutdown
  • Guard, crankcase
  • Starting aid, ether
  • Braking system: primary and secondary, wet disc, hydraulic; parking, hydraulic-released, spring-applied


  • Alternator, 115 ampere
  • Batteries (4), 12V, 1,000 CCA, maintenance free, high output
  • Electrical system, 24V
  • Lighting system: LED
  • Starting/charging receptacle


  • HVAC system, heat, AC, defrost
  • Thermostat control of HVAC system
  • Coat hook
  • Lunchbox platform with holding strap
  • Diagnostic connection (2)
  • 12V power ports (2)
  • Differential lock
  • Dome courtesy light
  • Horn, electric
  • T-handle implement control
  • Radio ready
  • ROPS/FOPS cab, pressurized
  • Keypad switches: rear engine start; throttle lock; wipers/washers; hazard lights; worklights on, off; information mode; messenger display; safety tab rocker switches, parking brake
  • Seat belt, static two-piece
  • Windows, sliding
  • Windshield wipers, front and rear windows, includes washers
  • Windows, laminated, zipped in
  • Mirror, rearview
  • Door lock
  • Messenger display gauges, warnings include: coolant temp; engine oil temp; hydraulic oil temp; DPF temp; fuel level; park brake; implement lockout; brake system, regeneration required; throttle lock; system voltage; secondary steering; bail down; differential lock; apron float; transmission hold; high beam lights; action lamp; engine speed, rpm; gear selection; DPF fill levels
  • Safety tab rocker switches
  • Seat: Cat Advanced Ride Management (ARM), Cat Comfort Series III, rotates 30 degrees
  • Steering wheel, tilt, telescoping, padded
  • Windows, right side emergency egress
  • Messenger display


  • Extended life coolant to -37° C (-34° F)


  • Advanced cushion hitch
  • Accumulators (cushion hitch and brake) with Canadian registration number (CRN)
  • Tow pin, front
  • Fenders, non-metallic
  • Heater, engine coolant 120V


  • Fast-fill fuel tank

Optional Equipment


  • Camera arrangement: Work Area Vision System (WAVS)
  • Cab beacon
  • Air horn
  • Air horn and beacon
  • Kingbolt housing
  • Rear wheel arrangement (set of 2)
  • Scraper draft arm package
  • Steering cylinder group (set of 2)