621H Wheel Tractor-Scraper

621H Wheel Tractor-Scraper

Quick loading, high travel speeds and the ability to load and dump on the run yield fast cycle times, allowing Cat Wheel Tractor-Scrapers to consistently deliver high productivity ...

Tractor Engine

Flywheel Power - Tractor/Scraper
304 kW (407 hp)

Scraper Bowl

Scraper Capacity - Heaped
Rated Load
Width - Cut - Outside Router Bits
Thickness - Cutting Edge
Struck Capacity
Maximum Hydraulic Penetration Force
Maximum Ground Clearance at Cutting Edge
Maximum Depth of Spread
Maximum Depth of Cut
Heaped Capacity
Maximum Apron Closure Force
Maximum Apron Opening


Top Speed - Loaded
1 Forward
2 Forward
3 Forward
4 Forward
5 Forward
6 Forward
7 Forward
8 Forward

Tractor Engine - Prior U.S. EPA Tier 3/EU Stage IIIA Configuration*

Maximum Power - All Gears - ISO 14396
Maximum Power Reference Engine Speed
Tractor Engine
Cat® C13 ACERT™

Tractor Engine - U.S. EPA Tier 4 Interim/EU Stage IIIB

Tractor Engine
Cat® C13 ACERT™
Maximum Power Reference Engine Speed
Maximum Power - All Gears - ISO 14396



Service Refill Capacities - Scraper

Non-Powered Wheel
1.1gal (US)
Fuel Tank
201.6gal (US)

Service Refill Capacities - Tractor

Windshield Washer Reservoir
1.3gal (US)
Engine Crankcase
8.75gal (US)
18.5gal (US)
45.8gal (US)
Final Drive - Each
5gal (US)
Cooling System
17gal (US)
Hydraulic Reservoir
22gal (US)


Steering Cylinder - Stroke
Steering Cylinder - Bore
Steering Circuit Flow
Secondary Steering Circuit Flow
Scraper Circuit Flow
Cushion Hitch Cylinder Stroke
Cushion Hitch Cylinder Bore
Cushion Hitch Circuit Flow
Push/Pull Bail Cylinder Bore
Push/Pull Bail Cylinder Stroke
Bowl Cylinder Bore
Bowl Cylinder Stroke
Apron Cylinder Bore
Apron Cylinder Stroke
Ejector Cylinder Bore
Ejector Cylinder Stroke


Cat® C13 ACERT™
Maximum Power

Weights - Machines Meeting U.S. EPA Tier 4 Interim/EU Stage IIIB Emission Standards

Push-Pull - Loaded - Based on a Rated Load
Push-Pull - Operating Weight - Full Fuel Tanks
Push-Pull - Shipping Weight - 10% Fuel
Standard - Loaded, Based on a Rated Load
Standard - Operating Weight - Full Fuel Tanks
Standard - Shipping Weight - 10% fuel

Weights - Machines Achieving Prior U.S. EPA Tier 3/EU Stage IIIA Emission Levels

Push-Pull - Loaded - Based on a Rated Load
Push-Pull - Operating Weight - Full Fuel Tanks
Push-Pull - Shipping Weight - 10% Fuel
Standard - Loaded, Based on a Rated Load
Standard - Operating Weight - Full Fuel Tanks
Standard - Shipping Weight - 10% fuel


Steering Angle - Right
Steering Angle - Left

Operator's Station

Ergonomic Layout

The all new H Series operator station is ergonomically designed for total machine control in a comfortable, productive and safe environment. All controls, levers, switches and gauges are positioned to maximize productivity and facilitate a reduction in operator fatigue.

Viewing Area

Designed for excellent all-around visibility and clear sight lines to the job site, the large viewing area offers exceptional visibility to the front of the machine as well as to the cutting edge. The air conditioning unit has been relocated to beneath the cab, allowing the operator enhanced visibility.

Operator Comfort

Spacious Cab

With a 21% larger cab, H Series scrapers offer a comfortable working space. The larger cab and wider door make getting in and out of the cab easier. The increased glass area enhances visibility around the machine.

Steering Column

The steering column and pedals have been relocated for more comfortable operation when the seat is angled during machine operation. The telescopic and tilt adjustable steering column maintains a comfortable driving position regardless of operator size.

Standard Comfort Features

The H Series cab is equipped with features designed to maintain operator comfort. Standard comfort features include: coat hook, lunchbox storage platform with strap, air conditioning, heat, and radio-ready.

Seat Options

H Series scrapers use the Cat Comfort Seat with additional travel to allow the operator to position themselves for optimal comfort and productivity. The seat rotates up to 30 degrees to the right for a more comfortable position during loading and 30 degrees to the left to make getting in and out of the cab easier. For unparalleled ride comfort, H Series scrapers are equipped with the Cat Advanced Ride Management (ARM) seat suspension which uses an active suspension to dampen vibration and minimize end-of-stroke shock loads to the operator.

Integrated Technologies

The optional Sequence Assist, Load Assist, and Cat Grade Control automate many repetitive operator tasks.

T-Handle Implement Control Lever

The redesigned control lever puts all of the scraper functions in the palm of the operator's hand. The low-effort lever and convenient push-button and thumb wheel controls are ergonomically placed for minimum arm movement.

Power Train - Engine

ACERT Technology

The Cat® C13 ACERT™ engine continues the evolutionary, incremental improvements that provide breakthrough engine technology built on systems and components developed by Caterpillar with proven reliability. The engine is available with either U.S. EPA Tier 3/EU Stage IIIA equivalent emission configurations or U.S. EPA Tier 4 Interim/EU Stage IIIB certified emission configurations to meet the needs of contractors around the world.


Machines equipped with engines meeting U.S. EPA Tier 4 Interim/EU Stage IIIB emission standards are equipped with a Cat Clean Emission Module to deliver the performance and efficiency that customers demand while meeting emission requirements. Machines equipped with the U.S. EPA Tier 3/EU Stage IIIA equivalent engines are equipped with a muffler in place of the Cat Clean Emission Module.

Cat Clean Emission Module (CEM)

CEM is an exhaust aftertreatment package consisting of a diesel particulate filter, and control systems. The CEM reduces particulate emissions using passive and active regeneration during normal engine operation.

Cat NOx Reduction System (NRS)

The Cat NOx Reduction System (NRS) captures and cools a small quantity of exhaust gas, then routes it into the combustion chamber where it drives down combustion temperatures and reduces NOx emissions.

Diesel Particulate Filter Regeneration

Regeneration is the removal of soot from the Diesel Particulate Filter (DPF). The Aftertreatment Regeneration Device (ARD) is used to regenerate the DPF. The DPF traps both particulates and ash, the ash is removed at regular service intervals.

Power Train - Transmission

Electronic Transmission

The Cat eight-speed forward one-speed reverse Electronic Clutch Pressure Controlled (ECPC) transmission features enhanced shift control logic with anti-hunt shift strategy for speed continuity, and to ensure constant shift times.

  • Tractor gears 1-2 - converter drive for increased torque, gears 3-8 - direct-drive for drive train efficiency. Scraper gears use converter drive for more torque in the cut.
  • Transmission Hold maintains converter drive for maximum rimpull or holds current gear for best control.
  • Programmable Top Gear manually sets top gear available (3rd-8th) to match conditions or speed.
  • Neutral Coast Inhibitor prevents transmission shifts into neutral while moving.
Smooth Transmission Gear Shifting

The 621H features ECPC Shift Torque Management (STM), with improved Shift Control Logic (SCL) and Part Throttle Shifting (PTS). These features allow smoother shifting and greater acceleration on grades while torque is maintained through the shift changes. SCL also provides automatic shift selection that is more specific to the desired machine operation, and downshifts when needed for maximum acceleration when increased throttle is applied. PTS allows shifting at lower speeds during part throttle operation, resulting in improved part throttle fuel economy, quieter machine operation, and better maneuvering in reduced speed operating conditions.

Brake Performance

The 621H uses hydraulically-actuated wet disc brakes for exceptional brake performance. The standard Cat Engine Brake reduces brake wear and enhances machine control.


Cushion Hitch

Electronically actuated with parallelogram-type linkage for exceptional strength, with two nitrogen accumulators (4) using free-floating pistons (8) to deliver a smooth ride for enhanced operator comfort and machine durability.

  • controlled oil flow (6) dampens rebound oscillation
  • leveling valve (7) applies pressure via an orifice (5) to automatically center the piston in load cylinder (1)
  • steel castings are used to eliminate many welded joints and increase strength
  • double-kingbolt design (2, 3) withstands high external forces, simplifies installation and removal
Lockout Switch

An operator-selectable lockout switch, located on the joystick, locks the cushion hitch down for improved control of the cutting edge during loading and dumping.

Nitrogen Accumulator

Vertically mounted hydraulic cylinder transfers road shocks to nitrogen accumulators. Nitrogen accumulator absorbs and dampens road shocks, thus preventing the loads from being transmitted to the hitch components or to the operator.

Non-Metallic Fenders and Fuel Tank

The new fuel tank is made of recyclable roto-milled polyethylene and keeps the fuel cleaner with controlled filtration and cleanout access ports. The new capacity of the new fuel tank has been increased, providing operators with 10 plus hour shifts depending on engine load factors. The new tractor fenders are made of the same highly durable, roto-milled polyethylene. The non-metallic fenders prevent material buildup when operating in sticky materials.

Scraper Bowl

Redesigned Bowl

The 621H uses a new bowl design than enhances productivity through a 9% increase in bowl capacity over previous models. The low profile design offers low resistance to incoming materials, while cellular constructions adds strength and dent resistance to the bowl sides and floor.

Hydraulic Lines Protection

Hydraulic lines durability is increased by routing them through the bowl sidewalls where they are protected from damage on the job site.

Ejection System

The powerful ejection system provides constant spreading control while minimizing carryback material. An overflow guard on the ejector helps retain material and keep it from spilling over onto the rear of the scraper.

Cutting Edges and Cat Ground Engaging Tools (GET)

A variety of Ground Engaging Tools (G.E.T.) options are available to optimize the machine for different material types and loading conditions. GET options include standard, serrated, and abrasion resistant material (ARM). Most are reversible to provide long life and reduced operating costs.

Loading Options


To achieve maximum productivity, the 621H should be push-loaded with a D8- or D9-size Track-Type Tractor.


The push-pull arrangement is recommended for applications that require a large amount of material to be moved very quickly at low cost per bank cubic meter (bank cubic yard). The push-pull arrangement concentrates the combined power of two machines onto one cutting edge. Push-pull scrapers work in pairs where the lead scraper is pushed through the cut by the trailing scraper. When the lead scraper is fully loaded, the trailing scraper lowers its bowl and is pulled through the cut by the lead scraper. The result is a self-loading system. The push-pull arrangement features a hydraulically-actuated bail and cushioned plate, which are bolted to the front of the tractor, and a hook that is attached to the rear of the scraper. Working together, push-pull scrapers can provide the lowest cost per meter (yard) for many applications. As a single-engine machine, the 621H push-pull arrangement is recommended for easy loading application with well maintained haul roads and grades of +5% or less.

Integrated Technologies

Sequence Assist

Sequence Assist uses integrated software and position-sensing cylinders to automate many of the tasks an operator performs when loading, hauling and dumping. The operator simply sets preferences for bowl and apron height and subsequently pushes a button to ready the machine for loading, then hauling, then dumping, and then the return to cut. The system automatically sets the cushion hitch, bowl height, apron, and ejector. Sequence Assist comes with a convenient load counter for tracking material moved. With Sequence Assist, up to 14 individual implement and machine commands are replaced by four touches of a button, allowing the operator additional time to prepare for the loading cycle and observation of the job site.

Load Assist

Load Assist builds on Sequence Assist by loading the bowl with the push of a button. As the machine enters the cut, the operator can activate Load Assist so the system takes over control of the cutting edge height, limiting tire spin based on integrated sensors and GPS technology to ensure consistent and full bowl loads. The operator is responsible only for the throttle, steering, and operating the apron. Load Assist helps make inexperienced operators productive very quickly.

Cat Grade Control

Cat Grade Control is an automatic system that helps you control costs by moving the maximum amount of material with the prime earthmover which often provides the lowest cost per unit of material moved. Using satellite positioning technology, the automatic system ensures cut protection by limiting how deep the scraper will dig. The optional system is available from the factory and fully integrated into the machine and works seamlessly with Sequence Assist and Load Assist. Additional benefits of Cat Grade Control include putting the site plan in front of the operator for increased efficiency and elimination of rework and using the scraper for site mapping.

Work Area Vision System (WAVS)

Cameras on the machine provide views of the cutting edge, right side and rear. The system enhances safety and provides a new way to see the cutting edge during loading and to see to the rear of the machine when performing push-load or push-pull work with another scraper.

Complete Customer Support


Make comparisons of the machines you are considering before you buy. Your Cat® dealer can help.


Consider the resale value, compare productivity and day-to-day operating costs and fuel consumption.


For the best operating techniques to increase productivity and your profit, turn to your Cat dealer for the latest training literature and trained staff.


Repair option programs guarantee the cost of repairs up front. Diagnostic programs such as S·O·SSM and Technical Analysis help you avoid unscheduled repairs.


Repair or rebuild? Your Cat dealer can help you evaluate the costs so you can make the right choice.

Product Support

Your local Cat dealership will be with you every step of the way with its unsurpassed worldwide parts support, trained technicians and customer support agreements.


Powered Access Ladder

A new powered access system option significantly reduces the effort required to climb into the cab. The system is a solid, stable angled ladder that folds out from underneath the cab. It is activated from a keypad located behind a service door at ground level. Controls are also located in the cab on a keypad. The ladder provides a rigid and angled base of support for easier climbing and descent. For added safety, the steps are illuminated by LED lights. An actuator under the cab operates the step. When not in use, the ladder retracts under the cab. An audible alarm sounds if the machine moves while the ladder is down. If power fails on the machine, the operator can raise or lower the steps manually using a lever inside the cab or outside next to the ladder's top step.

Access and Egress

Handrails and grab irons are provided for safe and secure entrance and exit of the cab as well as for performing daily maintenance.

Work Area Vision System (WAVS)

Cameras on the machine provide views of the cutting edge, right side and rear. The system enhances safety and provides a new way to see the cutting edge during loading and to see to the rear of the machine when performing push-load or push-pull work with another scraper.

Standard Equipment: