Engineered for demanding work in large dozing applications, the Caterpillar 844 Wheel Dozer is an ideal match for power generating utilities, clean up, road maintenance and production dozing at mines and in the general contracting industry.
Engine Model | Cat® 3412E |
Gross Power | — |
Operating Weight | — |
Engine Model | Cat® 3412E |
Gross Power | — |
Flywheel Power | — |
Net Power | — |
Flywheel Power - Caterpillar | — |
Flywheel Power - EEC 80/1269 | — |
Flywheel Power - ISO 9249 | — |
Flywheel Power - SAE J1349 (JAN90) | — |
Flywheel Power - DIN 70020 | 648 PS |
Bore | — |
Stroke | — |
Displacement | — |
Operating Weight | — |
Converter Drive - Forward 1 | — |
Converter Drive - Forward 2 | — |
Converter Drive - Forward 3 | — |
Converter Drive - Reverse 1 | — |
Converter Drive - Reverse 2 | — |
Converter Drive - Reverse 3 | — |
Direct Drive - Forward 1 | — |
Direct Drive - Forward 2 | — |
Direct Drive - Forward 3 | — |
Direct Drive - Reverse 1 | — |
Direct Drive - Reverse 2 | — |
Direct Drive - Reverse 3 | — |
Number of Forward Speeds | 3 |
Number of Reverse Speeds | 3 |
Output at 2,126 rpm and 6894 kPa (1,000 psi) | — |
Cylinder, Double Acting - Tilt and Tip, Bore and Stroke | 209.5 mm x 188 mm 8.25 in x 7.5 in |
Relief Valve Setting - Bulldozer (Large Pump) | — |
Relief Valve Setting - Tilt Cylinders (Small Pump) | — |
Minimum Turning Radius - Over Tires | — |
Hydraulic output at 2128 rpm and 1000 psi (6900 kPa) | — |
Relief Valve Setting | — |
Steering Angle | — |
Fuel Tank - Standard | — |
Cooling System | — |
Crankcase | — |
Transmission | — |
Hydraulic Tank | — |
Differential - Final Drives - Front | — |
Differential - Final Drives - Rear | — |
Hydraulic System - Implement and Brakes - Tank Only | — |
Hydraulic System - Steering and Engine Cooling Fan - Tank Only | — |
ROPS/FOPS | Meets SAE and ISO standards. |
Sound Performance Levels | Meets ANSI, SAE and ISO standards. |
Brakes | Meets SAE/ISO 3450 1996. |
Front | Fixed |
Rear | Oscillating ±11° |
Maximum Single-Wheel Rise and Fall | — |
Tire Choices | Two choices available. |
Standard Tire Size | Two choices available. |
Blade Capacities | 15.9 to 30.7 m3 20.7 to 40.2 yd3 |
Ground Clearance | — |
Is direct-electric 24-volt with a 75-amp alternator and two 12-volt 190-amp-hour batteries.
Is controlled without concern for cam profile limitations. Complete control of engine speed provides advantages in lower emissions, quieter operation, reduced smoke, improved hot or cold starting, white smoke cleanup and high altitude operation.
With the HEUI system will decrease proportionately with engine speed but can also electronically control the oil supply pressure. This complete control provides improved engine performance and decreased fuel consumption.
Reduces nitrous oxide (NOx) emissions and reduces engine combustion noise.
Lowers inlet charge temperature. Reduces thermal stresses that can cause premature wear of pistons, rings and liners.
Independent of engine speed, decrease smoke and emissions while improving response.
Provide maximum heat transfer for longer component life.
Maintains optimum oil temperature for proper cooling and pressure lubrication. Engine cooling provided is by the Multi-Row Modular radiator. Hydrostatic fan drive gives the standard cooling package 110° F ambient capability.
Allows the operator to modulate rimpull from 100 percent to 20 percent of maximum rimpull. After 20 percent of maximum rimpull is achieved, further pedal travel applies the brake. The torque converter is equipped with a lockup clutch for direct drive efficiency.
Modulates the amount of engine power sent to the wheels.
With Electronic Clutch Pressure Control provides direct drive efficiency in second and third forward gears and all three gears in reverse with higher speeds and improved fuel economy on long distance dozing.
Is the same transmission found in the 990 Series II wheel loader. Electronic shifting provides smooth consistent shifts with finger tip controls housed in the STIC controller. The transmission is built around a center shaft with a gear set cluster stacked end-to-end to distribute load, conserve space and transfer energy efficiently. Large diameter perimeter clutches coupled with high contact planetary gear sets provide high torque carrying capacity for long, trouble-free life.
Are fully hydraulic, completely sealed and never need adjustment. Disc face grooves provide cooling even when brakes are applied for a long, fade resistant life.
Provides a larger cooling oil reservoir and thicker separator plates than conventional brake designs. This gives the brake higher heat dissipation rates allowing higher capacity than conventional oil-disc brakes. Duo-cone seals are located between the wheel and the spindle.
Reduces service time. Conventional brakes require final drive disassembly. The axle-shaft brake design allows brake service while leaving the final drive intact. Reduced service time and machine downtime keeps operating costs low.
Are common with the Cat 990 Series II Wheel Loader.
Are four wheel, hydraulic, oil-dipped multiple disc brakes that are adjustment-free, completely enclosed and allow modulated engagement without slack adjusters.
Are fully modulated and the front and rear service brake circuits are isolated so one circuit can operate if pressure drops int he other circuit.
In order to meet EPA Tier 2 and EU stage II emissions requirements for the Year 2002, the software for the Cat 3412 HEUI engine has been changed and the cooling system upgraded to an AMOCS that utilizes the ATAAC system to achieve lower particulate, NOx and sound output. The proven AMOCS system is currently used on other Caterpillar models such as the 834G, 854G, 988G and 992G and with ATAAC technology effective with the 834G and 988G introduction.
Provides a separate cooling system for the intake manifold air complementing the engine jacket water cooling system. The ATAAC system routes hot, compressed air from the turbo and cools it with a single pass, air-to-air aluminum heat exchanger. The cooled compressed air is then delivered to the engine intake manifold. Providing the engine with cool compressed air greatly reduces the emissions produced, meeting Tier 2 requirements for a cleaner environment.
Isolates the AMOCS radiator and demand fan from the engine compartment with a shield allowing the radiator to receive outside ambient air through the side and top vents at a much lower temperature than the hot air from the engine compartment. This improves the system's efficiency and allows the radiator size to be decreased and the rear hood to be sloped, improving the rear viewing area. Also, sound levels are reduced due to the lower fan speed of a more efficient cooling system.
Is a Caterpillar exclusive technology that improves serviceability and increases cooling efficiency by 22 percent. Ambient working temperature for the standard 844 is 43° Celsius (110° Fahrenheit). A high ambient cooling package with a 50° Celsius (122° Fahrenheit) capacity is available as an attachment.
Is a key benefit. Tubes are welded to a large, thick header, providing the strength of the tube-to-header joint that reduces the possibility of coolant leaks. The AMOCS modular core design allows removal of a single core without removing the entire radiator - reducing downtime through ease of serviceability. Replacing the individual core also reduces repair costs.
Offers increased cooling capacity. Coolant travels from the engine to the fan side of the bottom tank, up the fan side of each core, over the top, down the engine side of the core, into the engine side of the bottom tank and back to the engine. The improved flow pattern allows the coolant to pass through the radiator twice for better cooling. The AMOCS design improves serviceability, reduces downtime and increases cooling capability.
Are more than 90 percent robotically welded. This provides highly consistent welds with deep plate penetration and excellent plate fusion. The benefit is greater fatigue strength and longer life than with conventional welding methods.
In the engine end-frame are used in critical high-stress areas to help spread the load and reduce the number of parts. The casting for the rear trunnion mount also serves as an engine mount, which provides a load path for the weight and torque of the engine to travel down to the trunnion and then on through to the axle. Other castings used in the engine-end frame include: front trunnion mounts, steering cylinder brackets, articulation stops and lock link.
Absorbs shock loads and torsional forces, solidly maintaining alignment for hitch pins and driveline.
Provides maximum structural strength to resist twisting loads during dozing applications.
Pivot on double-tapered roller bearings and are shaped to direct stress away from the end of the weld, resulting in a smoother transition of stress loads.
Helps square up the frame and provides more clearance for hydraulic lines. Double tapered roller bearings and hardened pins resist both horizontal and vertical loads to increase life. The spread hitch also makes service access easier.
Are designed to use mushroom and cup-shaped ISO mounts, reducing component vibration and sound levels. The engine mounts directly to the rear cross member, simplifying and improving load transfer structure.
One for lift/tilt/tip and brakes, while the other is for steering and the hydraulically-driven engine cooling fan. Benefits of two systems are increased cooling and elimination of cross-contamination. If one system runs hot or is contaminated, the other will be unaffected.
O-ring face seals and large-bore lift and tilt cylinders top off the hydraulic system, delivering the performance and durability owners expect. Reliable components reduce leaks and help protect the environment.
Is used for engine, transmission and hydraulic cooling. A variable displacement pump drives the fan's hydraulic motor so that fan speed varies with coolant temperature. The fan draws only the power needed for cooling, reducing fuel consumption and increasing efficiency.
Is designed for precise and productive dozing while helping to retain load control with increased capacity for lighter materials. Wing angles help retain the load while dozing.
Combines the characteristics of the S and U blades into one package. Provides increased capacity with the addition of short wings which include only the dozer end bits without sacrificing spreading characteristics of straight blades.
Has the same configuration as the semi-U blade but is built with thicker plates for more severe applications.
Hydraulically operates blade raise, lower, tilt and tip.
Features four positions: raise, hold, lower and float with detente hold on float.
Offers operator selected single or dual-tilt and fingertip control for tip operation.
Comes from the single-lever lift/tilt/tip control that is floor mounted and cable actuated with pressure compensation for tilt/tip.
Can be selected by the operator by using a switch located on top of control lever. A generous range of tilt motion enables excellent control for dozing.
Is spacious and incorporates innovations for operator comfort and productivity, include an excellent viewing area, interior sound levels below 75 dB(A), Caterpillar Comfort Series seat, standard coat hook, cup holder, storage bin, sun visor and intermittent wet-arm wipers. It is also radio-ready for two-way radios.
Is a revolutionary system that integrates steering and transmission into a single controller. Simple side-to-side motions of the operator's left arm turn the machine right or left. Transmission shifting forward, neutral or reverse is controlled by the operator's fingers, and gear selection is controlled by the operator's thumb. These factors combine to produce a fluid motion that reduces effort and allows the operator to work the machine for long periods of time with little or no fatigue.
Operates the Impeller Clutch Torque Converter for about the first inch of travel, then engages the brakes. Within the first inch of pedal travel, rimpull can be controlled from 100 percent to 20 percent.
With air suspension and retractable seat belt is designed for comfort and support. Seat cushions reduce pressure on the lower back and thighs while allowing unrestricted arm and leg movement. The seat has three height levels. The retractable seat belt remains off the floor and is easy for the operator to reach.
Allows quicker cycle times by shifting from first forward to second reverse.
Allows the operator to preset the engine speed and concentrate on productivity. The throttle lock can be deactivated by pressing the brake pedal.
Are adjustable fore and aft, with a height-adjustable armrest so operators of any size can find a comfortable operating position. A single lever control allows operator to control blade functions: lift/lower, tip and tilt. The switch control on top of control lever allows option of single or dual-tilt operation.
Is activated when the operator presses a switch on the console. The 844 automatically shifts from torque converter drive to direct drive when a set speed in second and third forward or all gears in reverse is reached, providing faster travel speeds and less fuel consumption.
Enhances viewing in all directions. Bonded glass in the front window eliminates distracting metal frames with the best operator visibility to the blade.
In addition to the servicing features built into the engine, the 844 includes:
For easy, comfortable access for operators and service personnel.
Provide excellent access to service points, engine oil dipstick, diagnostic connector, engine oil and fuel filters, starting receptacle, air filter indicator, air filters, fuel/water separator and the ether starting aid cartridge.
Provides passage to hydraulic filter, fuel fill and transmission filters through easy-to-open doors.
Provides entrance to transmission and pumps when service is required.
Provides access to fuses and electronic control modules.
Are accessible through hinged doors in bumper.
On the radiator guard provide easy access for radiator cleanout.
Accessible at ground level, make daily lube maintenance quick and easy.
In the hydraulic tanks and radiator provide quick check for fluid levels.
Make detailed comparisons of the machines under consideration before purchase. Cat dealers can estimate component life, preventative maintenance cost and the true cost of lost production.
Look past initial price. Consider the financing options available as well as the day-to-day operating costs. Look at dealer services that can be included in the cost of the machine to yield lower equipment owning and operating costs over the long run.
Cat dealers offer a variety of product support agreements and work with customers to develop a plan that best meets specific needs. These plans can cover the entire machine, including attachments, to help protect the customer's investment.
You will find nearly all parts out our dealer parts counter. Cat dealers use a worldwide computer network to find in-stock parts to minimize machine downtime. Save money with genuine Cat Reman parts. You receive the same warranty and reliability as new products at cost savings of 40 to 70 percent.
Improving operating techniques can boost your profits. Your Cat Dealer has training videotapes, literature and other ideas to help you increase productivity.
Choose from your dealer's range of maintenance services when you purchase your machine. Repair option programs guarantee the cost of repairs up front. Diagnostic programs such as S*O*SSM and Coolant Sampling and Technical Analysis help you avoid unscheduled repairs.
Repair, rebuild or replace? Your Cat dealer can help you evaluate the cost involved so you can make the right choice.
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