988K Millyard Arrangement

988K Millyard Arrangement

988K Millyard Arrangement


Introduced in 1963, the 988 has been the industry leader for 50 years. Focused on helping our customers succeed, we have continued to build upon each new series. The 988K continues our legacy of reliability, performance, safety, operator comfort, serviceability, and efficiency. The 988K Millyard Arrangement is designed to meet the demands of millyard applications. The features of the 988K Millyard work together to provide a durable and reliable machine to meet the needs of the modern millyard.

Cat® C18 Engine

The Cat C18 engine is built and tested to meet your most demanding applications while meeting U.S. EPA Tier 4 Final/EU Stage IV Technology, Tier 2 Equivalent emission standards.

  • Fully integrated electronic engine controls works in concert with the entire machine to make your fuel go farther.
  • Use less fuel idling with Engine Idle Shutdown.
  • Maximized durability with Delayed Engine Shutdown.

Cat Planetary Powershift Transmission

Featuring all new Advanced Productivity Electronic Control Shifting (APECS) transmission controls provides greater momentum on grades and fuel savings by carrying that momentum through the shift points.

Impeller Clutch Torque Converter (ICTC)

Enable your operators to maximize efficiency by varying machine rimpull while putting more horsepower to hydraulics.

  • Reduced tire wear
  • Enables full throttle shifts for faster cycle times
  • Provides smooth approach to the dump target for less spillage and faster cycle times.

Cat Torque Converter with Lock-up Clutch

  • Eliminates TC losses while lowering system heat
  • Improves travel speeds
  • Reduces cycle times in load and carry operations

Economy Mode

Enabling maximum productivity and efficiency, all day every day. The 988K systems work hard to save you fuel through advanced technologies. Utilizing On Demand Throttle, operators maintain normal operation with the left pedal and implements while the 988K manages the engine speed.

  • Provides similar control and feel to our traditional throttle lock feature.
  • Efficiency of manual throttle and the ergonomics of throttle lock.
  • Reduced fuel consumption by up to 20% compared to the 988H.

Robust Structures

Your bottom line is improved by highly durable structures that achieve multiple life cycles and withstand the toughest loading conditions.

  • Full box-section rear frame resists torsional shock and twisting forces.
  • Heavy-duty steering cylinder mounts efficiently transmit steering loads into the frame.
  • Axle mounting has been optimized for increased structural integrity.
  • Lower hitch pin, frame plate, and bearing size have been increased for longer life.

Front Linkage

To ensure long life and reliability, the linkage pin joints feature a greased pin design with an auto lube system attachment available from the factory.

Steering and Transmission Integrated Control System (STIC™)

Experience maximum responsiveness and control with STIC that combines directional selection, gear selection and steering into a single lever.

  • Simple side-to-side motion turns machine right or left, minimizing operator movements.
  • Easy to operate finger controlled gear selection.
  • Smoother, faster cycles and less operator fatigue through the use of low effort integrated controls.

Cat Planetary Powershift Transmission

Building your success begins with a best-in-class transmission designed specifically for mining applications.

  • Consistent, smooth shifting and efficiency through integrated electronic controls that utilize Advanced Productivity Electronic Control Strategy (APECS).
  • Long life and reliability through heat treat gear and metallurgy.
  • Four forward and three reverse speeds to match your application.

Cat C18 Engine

Durability and efficiency at the heart of your 988K comes from the Cat C18 Engine. Optimum performance is built in through the use of a 6 cylinder, four-stroke design.

  • Optimized performance and quick engine response with an electronic control module.
  • Reliable efficiency with complete control over injection timing, duration and pressure with Mechanically Actuated Electronic Unit Injection (MEUI™).
  • Extended engine life and improved fuel efficiency with reduced rated speed.
  • Designed to meet U.S. EPA Tier 4 Final/EU Stage IV emission standards, Tier 2 Equivalent emission standards.

Electro Hydraulic Controls

Operators increase productivity with our responsive implements feature.

  • Operate comfortably through electronically controlled hydraulic cylinder stops.
  • Handle easy-to-use soft detent controls.
  • Conveniently set automatic implement kickouts from inside the cab.


Your operator's productivity is enhanced with our clean, comfortable cab environment.

  • Experience reduced vibrations from isolation cab mounts and seat air suspension.
  • Maintain desired cab temperature with automatic temperature controls.
  • Pressurized cab with filtered air.
  • Sound level reduced to a quiet 71 dB(A).
  • Convenient floor storage tray/lunch box.

Cat Product Link™

Cat Product link allows remote monitoring of equipment to improve overall fleet management effectiveness. Events and diagnostic codes, as well as hours, fuel, idle time and other information are transmitted to a secure web based application, VisionLink®. VisionLink includes powerful tools to convey information to users and dealers, including mapping, working and idle time, fuel level and more.

The 988K has many design features that help you succeed by reducing your downtime.

  • Safe and convenient service with ground level or platform access and grouped service points.
  • Swing-out doors on both sides of the engine compartment provide easy access to important daily service checks.
  • Swing-out radiator system with 6 fins per inch cores for easier cleaning.
  • Auto-reversing fan to keep the cooling system clear of debris.
  • Ecology drains for ease of service and prevention of spilling potential environmental contaminants.
  • Reduce downtime with VIMS system notifications so your operators and technicians can resolve any problems before failure.
  • Ground level access to transmission control valves.

Legendary Cat Dealer Support

A valued partner, your Cat dealer is available whenever you need them.

  • Preventive maintenance programs and guaranteed maintenance contracts.
  • Best-in-class parts availability.
  • Improve your efficiency with operator training.
  • Genuine Cat Remanufactured parts.

Machine Access

  • Left and right hand stairs with 45 degree angle allow operators to safely get on and off the 988K.
  • Continuous walkway with metallic non-skid surfaces are designed into the service areas.
  • Maintain three points of contact at all times through ground level or platform accessible service areas.

Sustainable Benefits

The 988K is designed to maximize efficiency and productivity while conserving natural resources.

  • Burns up to 20% less fuel than the previous model to minimize your carbon footprint.
  • Engine Idle Shutdown can help you save fuel by avoiding unnecessary idling.
  • Reduce waste with our maintenance free batteries.
  • Built for multiple lives, the Cat 988 is one of the most rebuilt products. To assist with maximizing machine life, Caterpillar provides a number of sustainable options such as our Reman and Certified Rebuild programs. In these programs, reused or remanufactured components can deliver cost savings of 40 to 70 percent, which lowers operating cost while benefiting the environment.
  • Caterpillar offers retrofit packages to bring new features to older machines, maximizing your resource. And, when you go through the Cat Certified Rebuild program, these retrofit kits are part of the rebuild process.

Wooden Forks

Dual top clamps close down to the tine tips, their curvature maximizes carry capacity. Built to match the task of unloading trucks. An open, high visibility design allows operators to see the job at hand, work faster and more efficiently.

Woodchip Buckets

Extra capacity and loading characteristics make this bucket style perfect for handling woodchips. Available in direct pin on models or for use with the Cat Quick Coupler System.

Cat Full Width Forks

Dual top clamps are connected to allow maximum capacity while still closing between the tines allowing partial loads to be handled.


  • Lift Arms

    • High load stresses are absorbed by the solid steel lift arms.
    • Enhance strength in key pin areas through the use of one piece castings.
    • Stress relieved lift arms increase durability and lengthen time to repair.

  • Impeller Clutch Torque Converter (ICTC) and Rimpull Control System (RCS)

    Lower your cost per ton utilizing advanced ICTC and RCS for modulated rimpull.

    • Reduce tire slippage and wear by modulating rimpull from 100 to 25 percent while depressing left pedal. After 25 percent rimpull is achieved the left pedal applies the brake.
    • Reduce the potential for wheel slippage without reducing hydraulic efficiency with RCS.
    • Improve fuel efficiency in certain applications with our lock-up clutch torque converter providing direct drive.

  • Positive Flow Control Hydraulics

    Increase efficiency through our Positive Flow Control (PFC) Hydraulic System. PFC has concurrent pump and valve control. By optimizing pump control, hydraulic oil flow is proportionate to implement lever movement.

    • Fast, productive cycles are enabled by the fully variable implement pump.
    • Increase bucket feel and control through increased hydraulic response.
    • Consistent performance and efficiency with lower system heat.
    • Full hydraulic flow down to 1,400 engine rpm enabled by flow sharing technology.

  • Steering System

    Confident loader operation starts with precise machine control enabled by the 988K's load sensing hydraulic steering system.

    • Increase efficiency with our variable displacement piston pumps.
    • Achieve precise positioning for easy loading in tight areas with 37 degrees of steering articulation.
    • Enhance operator comfort with integrated steering and transmission control functions.

  • Filtration System

    Benefit from extended performance and reliability of your hydraulic system with our advanced filtration system.

    • Case drain screens.
    • Hydraulic oil cooler return filter.
    • Pilot filter.
    • Return screens inside hydraulic tank.
    • Axle oil cooler screens if equipped.

  • Your operators can work more efficiently and stay comfortable with our customer-inspired cab features.

  • Entry and Exit

    Enter and exit the cab easily and safely with these newly designed, ergonomic features.

    • Fold up STIC steer/armrest.
    • Reduced access stairway angles.
    • Standard stairway lighting.

  • Cat Comfort Series III Seat

    Enhance comfort and reduce operator fatigue with Cat Comfort Series III seat.

    • Mid back design and extra thick, contoured cushions.
    • Air suspension system.
    • Easy-to-reach seat levers and controls for six way adjustments.
    • Seat-mounted implement pod and STIC steer that moves with the seat.
    • 76 mm (3 in) wide retractable seat belt.

  • Control Panel

    Ergonomic placement of switches and Information display keep your operators comfortable all day every day.

    • Large backlit membrane switches feature LED activation indicators.
    • Switches feature ISO symbols for quick function identification.
    • Two position rocker switch activates the electro hydraulic park brake.

  • The 988K electronic systems have been completely integrated to function as one machine. This integration creates a smart machine and more informed operator, maximizing the productivity of both.

  • Third generation VIMS ™ system

    We have worked hard to help our customers and operators perform at their best through our Vital Information Management System (VIMS 3G).

    • Easy-to-view graphical information display features a large touch screen interface.
    • Intuitive operation and easy navigation with our enhanced user interface.
    • Decrease service time by keeping operators informed about machine system malfunction or operation.

  • We are constantly improving our products in an effort to provide a productive and safe work environment for the operator and those who work on your job site.

  • Visibility

    • Optional heated mirrors ensure good visibility for safe operation.
    • Standard Cat Vision or optional Cat Detect with radar increase operator awareness around the machine.
    • Optional HID or LED lights provide excellent workspace visibility.
    • Optional cab mounted LED warning beacons.

  • Operator Environment

    • Reduced vibrations to the operator with isolated cab mounts and seat mounted implement and steering controls.
    • Low interior sound levels down to 70 dB(A) on standard machine.
    • Pressurized cab with filtered air.
    • Standard 76 mm (3 in) seat belts on the operator seat.

  • Forks and Buckets

    Available for both the 988H and 990H, Millyard and Logging Forks are designed to move wood in the millyard. Woodchip Buckets are designed with performance characteristics to bring productivity and fuel efficiency to load-and-carry work in the yard.

  • Sawmill Forks

    A single top clamp closes down between the tines, allowing individual logs to be picked and placed with ease. An open, high visibility design allows operators to see the job at hand, work faster and more efficiently.

  • Standard Equipment
  • Optional Equipment
  • Specs
  • Docs

Standard Equipment

  • NOTE
    • Standard and optional equipment may vary. Consult your Cat dealer for details.
    • Alarm, back-up
    • Alternator, single 150 amp
    • Batteries, dry
    • Converter, 10/15 amp, 24V to 12V
    • Lighting system (halogen, work lights, access and service platform lighting)
    • Starting and charging system, 24V
    • Starter emergency start receptacle
    • Starter lockout in bumper
    • Transmission lockout in bumper
    • Graphical Information Display, displays real time operating information, performs calibrations and customizes operator settings
    • Air conditioner
    • Cat Detect Vision, rear vision camera system
    • Cab, sound suppressed and pressurized, integrated rollover protective structure (ROPS/FOPS) radio ready for entertainment, includes antenna, speakers and converter (12-volt 5-amp) and power port
    • Controls, lift and tilt function
    • Heater, defroster
    • Horn, electric
    • Instrumentation, gauges: - Coolant temperature - Engine hour meter - Hydraulic oil temperature - Power train oil temperature
    • Light, cab, dome
    • Lunchbox, beverage holders
    • Mirrors, rearview (externally mounted)
    • Rimpull Control System
    • Seat, Cat Comfort (cloth), air suspension, six-way adjustable
    • Seat belt, retractable, 76 mm (3 in) wide
    • STIC Control System
    • UV glass
    • Transmission gear indicator
    • Vital Information Management System (VIMS) with Graphical Information Display: External Data Port, Customizable Operator Profiles, Cycle Timer, Integrated Payload Control System
    • Wet-Arm wipers/washers (front and rear): - Intermittent front and rear wipers
    • Lights, directional
    • Swing out radiator system with 6 fpi radiator cores
    • Auto-reversing fan with adjustable controls and manual cycle
    • Hinged, perforated side doors
    • Brakes, oil-cooled, multi-disc, service/secondary
    • Case drain screens
    • Crankcase guard
    • Electro hydraulic parking brake
    • Engine, C18 MEUI diesel, turbocharged/aftercooled
    • Ground level engine shutoff
    • Turbine precleaner, engine air intake
    • Radiator, Next Generation Modular (NGMR)
    • Starting aid, ether, automatic
    • Throttle lock, electronic
    • Torque converter, Impeller Clutch (ICTC) with Lock up clutch (LUC), Rimpull Control System
    • Transmission, planetary powershift, 4F/3R electronic control
    • Automatic bucket lift kickout/positioner
    • Base machine price includes a rim allowance
    • Hydraulically driven demand fan
    • Couplings, Cat O-ring face seals
    • Doors, service access (locking)
    • Ecology drains for engine, radiator, hydraulic tank
    • Fuel tank, 731 L (188 gal)
    • Hitch, drawbar with pin
    • Hoses, Cat XT™
    • Hydraulic, steering and brake filtration/screening system
    • Cat Clean Emission Module
    • Oil sampling valves
    • Premixed 50% concentration of extended life coolant with freeze protection to -34° C (-29° F)
    • Rear access to cab and service platform
    • Steering, load sensing
    • Toe kicks
    • Vandalism protection caplocks

Optional Equipment

  • NOTE
    • Standard and optional equipment may vary. Consult your Cat dealer for details.
    • -50° C (-58° F) antifreeze
    • Engine oil change system, high speed, Wiggins
    • Engine block heater 120V or 240V
    • High ambient cooling - software
    • Cab precleaner
    • AM/FM/CD/MP3 radio
    • Satellite Sirius radio with bluetooth
    • LED warning strobe
    • CB radio ready
    • Window pull down visor
    • Front and rear roading fenders
    • Fast fill fuel system (Shaw-Aero)



Long Name:
988K Millyard Arrangement
988K Millyard Arrangement


Net Power
541 HP / 403 kW
Engine Model
Cat® C18 ™
Net Power - SAE J1349
541 HP / 403 kW
5.7 in / 145 mm
7.2 in / 183 mm
1105 in³ / 18.1 l
Torque Rise
58 % / 58 %
Rated Speed
Peak Power Speed - 1,500 rpm - Gross - ISO 14396
580 HP / 432 kW
Peak Power Speed - 1,500 rpm - Net Power - SAE J1349
541 HP / 403 kW
U.S. EPA Tier 4 Final/EU Stage V Technology or Tier 2 Equivalent
Peak Torque - 1,200 rpm
2104 lb/ft / 2852 N·m
Gross - ISO 14396
580 HP / 432 kW
Peak Power Speed
Peak Power Speed - 1,500 rpm - Gross - SAE J1995
588 HP / 439 kW


Fork End Area
69 ft² / 6.4 m²

Operating Specifications

Operating Weight
139920 lb / 63600 kg
Tipping Load - Straight
78115 lb / 35500 kg
Tipping Load - Articulated 37°
68005 lb / 30910 kg


Transmission Type
Forward - 1
4 mile/h / 6.5 km/h
Forward - 2
7.2 mile/h / 11.6 km/h
Forward - 3
12.7 mile/h / 20.4 km/h
Forward - 4
21.6 mile/h / 34.7 km/h
Reverse - 1
4.7 mile/h / 7.5 km/h
Reverse - 2
8.3 mile/h / 13.3 km/h
Reverse - 3
14.4 mile/h / 23.2 km/h
Direct Drive - Forward 1
Lock-up disabled
Direct Drive - Forward 2
7.8 mile/h / 12.5 km/h
Direct Drive - Forward 3
13.9 mile/h / 22.3 km/h
Direct Drive - Forward 4
24.4 mile/h / 39.3 km/h
Direct Drive - Reverse 1
5 mile/h / 8 km/h
Direct Drive - Reverse 2
8.9 mile/h / 14.3 km/h
Direct Drive - Reverse 3
15.8 mile/h / 25.5 km/h

Hydraulic System - Lift/Tilt

Maximum Flow
13.7 gal/min / 52 l/min
Pilot System
Variable displacement piston
Maximum Flow at 1,400-1,860 rpm
153 gal/min / 580 l/min
Relief Valve Setting - Main
580 psi / 4000 kPa
Cylinders, Double Acting - Tilt, Bore and Stroke
292 mm × 671 mm (11.5 in × 26.4 in)
Cylinders, Double Acting - Lift, Bore and Stroke
235 mm × 976 mm (9.25 in × 38.4 in)
Lift/Tilt System
Variable displacement piston
Lift/Tilt System - Circuit
EH- Positive Flow Control, Flow Sharing
Relief Valve Setting - Lift/Tilt
4641 psi / 32000 kPa

Service Refill Capacities

Fuel Tank
188 gal (US) / 712 l
Cooling System
31.7 gal (US) / 120 l
15.9 gal (US) / 60 l
31.7 gal (US) / 120 l
Differential - Final Drives - Front
49.1 gal (US) / 186 l
Differential - Final Drives - Rear
49.1 gal (US) / 186 l
Hydraulic System - Tank Only
63.4 gal (US) / 240 l
Hydraulic System Factory Fill
125.5 gal (US) / 475 l
Diesel Exhaust Fluid Tank
8.7 gal (US) / 33 l

Dimensions - Millyard Linkage

Fork Top Clamp Opening
12.3 ft / 3741 mm
Dump Angle at Maximum Lift
39.4 ° / 39.4 °
Ground to Top of Hood
10.9 ft / 3334 mm
Front Axle Centerline to Fork Tip
15.6 ft / 4765 mm
Fork Height at Maximum Lift
15.3 ft / 4660 mm
Wheel Base
14.9 ft / 4550 mm
Ground to Lower Hitch Clearance
1.9 ft / 568 mm
Rear Axle - Centerline to Bumper
10.5 ft / 3187 mm
Ground to Center of Front Axle
3.2 ft / 978 mm
Maximum Overall Length
41 ft / 12502 mm
Ground to Top of ROPS
13.8 ft / 4221 mm
Fork Height with Level Arms
8.1 ft / 2468 mm
Ground to Bumper Clearance
3.1 ft / 933 mm
Hinge Pin Height at Maximum Lift
16.1 ft / 4918 mm
Ground to Top of Exhaust Stacks
13.8 ft / 4214 mm


Oscillation Angle


SAE J1473 OKT90, ISO 3450:1992

Hydraulic System - Steering

Steering System - Circuit
Pilot, load sensing
Steering System - Pump
Piston, variable displacement
Relief Valve Setting - Steering
4351 psi / 30000 kPa
Steering Cycle Times - High Idle
3.4 s / 3.4 s
Steering Cycle Times - Low Idle
5.6 s / 5.6 s
Maximum Flow
71.3 gal/min / 270 l/min
Total Steering Angle
74 ° / 74 °

Sound Performance - Standard

Operator Sound Level (ISO 6396)
71 dB(A) / 71 dB(A)
Machine Sound Level (ISO 6395)
111 dB(A) / 111 dB(A)

Sound Performance - Suppression

Machine Sound Level (ISO 6395)
109 dB(A) / 109 dB(A)
Operator Sound Level (ISO 6396)
70 dB(A) / 70 dB(A)