Building on Caterpillar's 40+ years' experience designing and manufacturing skidders, the Cat® D Series Wheel Skidder delivers more productivity at lower operating cost. Get more wood to the landing faster in a stable machine with a roomy, comfortable environment for the operator. Advanced hydraulics speed up multi-functioning and cycle times and give you more lift capacity. The D Series runs cool and is designed to keep debris from collecting inside the machine. Tilting cab and other access points cut the time needed for daily maintenance and servicing.
The system is arranged in two panels. The engine radiator and coolers for hydraulic oil and fuel are stationary, and a swing-out hinged panel houses the air conditioner condenser and air-to-air after cooler (ATAAC). The transmission cooler is a water-to-oil type using engine coolant for cooling. All components are within easy reach and the cooling system can be cleaned from both sides. The fan shroud can be easily removed for increased service access below the cooling system.
Cool and clean
The cross-flow configuration and compartmentalization of the engine and cooling system maximize efficiency and reduce debris collection. The fan shroud and baffling requires cool ambient air to be pulled in from the side — not from the engine compartment. Air is exhausted on the opposite side. This prevents hot air from circulating and debris from collecting in the engine compartment. Fin spacing is coarse to allow debris to pass through more easily and reduce plugging.
The oversized fan spins at a slower speed, only as fast as needed to maintain proper operating temperatures. In colder weather or when the machine is first started the fan spins more slowly to conserve power and fuel and reduce noise. The fan automatically reverses every 20 minutes of run time. The operator can activate reversal between cycles through a manual override.
The service brake components are housed inside the axles, protecting them from dirt, dust and moisture. An inline parking brake is spring activated and hydraulically released.
The field proven Cat countershaft powershift transmission easily matches engine power to the load size and ground conditions. The D Series gears are more evenly distributed in the working range to maximize performance in tough terrain and ground conditions.
Electronic Clutch Pressure Control
Electronic Clutch Pressure Control (ECPC) provides a valve for each clutch in the transmission to regulate and modulate the individual clutches based on current operating conditions and operator input. The result is smoother, faster, more efficient gear changes maximizing performance, durability and operator comfort.
Lock-up torque converter
The lock-up torque converter allows the machine to ease smoothly into a start when the skidder has a heavy load in the grapple, which is easier on the tires and chains. Then, depending on ground speed and conditions, the lock-up clutch automatically engages and the transmission goes into direct drive for high efficiency hauling and up to 15% faster travel speeds in the same gear.
Independent front/rear differentials
The D Series is easy to maneuver even in dense woods and slippery or steep conditions. In normal operation, all four wheels move independently. In poor ground conditions, the independent front and rear differential locks can be engaged separately for better pulling performance and to maintain maneuverability. The locks are hydraulically actuated and can be engaged on the go.
Cat ToughGuard™ hoses increase hose life in the grapple, arch, boom and across the hitch. The ToughGuard cover consists of a layer of UHMW polyethylene bonded to the rubber cover, providing exceptional abrasion resistance. O-ring face seals assure rocksolid connections that maintain pressure and reduce oil leaks, particularly along the arch and boom and through the center hitch.
Fast cycle times
While steering has full priority, the new hydraulic system allows plenty of flow to continue to the main control valve. You can steer, back up and activate arch, boom and grapple functions at the same time. Cycle times are significantly faster increasing productivity.
Job sites today demand more of the skidder than delivering harvested trees to the landing. The skidder is often the workhorse called on to move the knuckeboom loaders. Hydraulic system pressure boosts of 15% for the 525D and 535D and 23% for the 545D and 555D, matched to the boom length, increase the lift capacity of the D Series. You can more quickly move your loaders to a new job site and get on with the work.
The auto-grab feature monitors tong pressure and adjusts as needed to securely hold grapple loads while skidding. For more secure transport of heavy loads, auto-grab pressures are higher in the D Series as a result of the increased system pressures. A switch on the right-hand joystick activates this feature.
The electrohydraulic grapple, blade and winch controls give you more precision operating the skidder while eliminating hydraulic pilot lines in the cab.
The fenders extend tire life by providing maximum coverage in both grapple and cable skidding applications. The cable fenders continue to be the best in the market. The angle of the grapple fender support plates provide additional rigidity. Support structures between the fender and the rear frame provide even greater support.
Front and rear frames are robot welded to ensure the highest level of quality and durability. Box section construction is utilized to support bending and twisting forces created by heavy loads. Field proven steering cylinder mounts distribute forces over a large area to maximize life. The solid steel nose of the D Series is built to withstand the toughest applications.
Field-proven center hitch
The field-proven center hitch design features large dual tapered roller bearings in both the upper and lower hitch with 3 in. (76 mm) diameter pins providing maximum durability. The spread between the upper and lower hitch pins reduce horizontal loading on the pins and bearings for greater durability and extended life. The extra room also increases hydraulic hose clearance and makes hose routing easier.
The pin-mounted blade in the D Series is more durable and feature short, large diameter pins. The industries only blade with bolt-on cutting edges made of abrasion-resistant, heat-treated steel significantly increases the life of the blade. Also, the angle of the blade to the ground when pushing dirt or debris is optimized for smoother, more efficient blading.
Strengthened bottom guarding
Bottom guards, including guarding on the rear axle, protect the underside. The increased rigidity of the lower frame provides extra support to the bottom guarding to prevent damage from riding over stumps and rocks.
The retrieval winch runs off the skidder's main hydraulic pump and is designed to support machine and truck retrieval. All single or dual function models can be equipped with a retrieval winch.
All 525D, 535D and 545D single or dual function models can be equipped with a logging winch for more versatility in regions where the ability to do both grapple and cable skidding is needed. The logging winch is standard in all cable arch configurations for production cable logging applications. A dedicated hydrostat pump and internal gearing changes boost the speed of the logging winch to optimize productivity in cable logging applications.
Check status of the machine's systems with the clean and clear monitor display:
Check status of the machine's systems with the clean and clear monitor display:
Indicator lights provide additional information such as auto-grab, torque converter lock-up, and differential lock engagement.
If a system problem occurs, the monitor will display an easy-to-understand text explanation, along with applicable fault codes.
If a condition requires immediate action, a warning buzzer will sound. The operator must acknowledge the warning to turn off the alarm. Depending on how serious the warning, the alarm will continue to sound until the condition is addressed.
Everything the system does is recorded in the system log for monitoring machine health and operator activity.
The cab offers plenty of legroom for tall operators and space to store tools and personal items. The cab is isolation-mounted to the skidder frame to minimize vibration and positioned between the axles for the most comfortable ride possible, no bucking.
The cab is pressurized and sealed (with side windows closed) for efficient heating and cooling and sound control. Tight door and window casings also keep out dust. The sealed cab keeps engine and job site noise low.
Cat Comfort Seat
The standard Cat Comfort Seat swivels 30° to the right so you can watch skidder and grapple operations. Beyond adjustments for seat and armrest position, recline and lumbar, the high back seat can be adjusted to accommodate height and weight and ride firmness preferences to reduce fatigue. The grapple is controlled through the seat-mounted joystick. You can rest your forearm on the armrest and have full control in your hand. Steering with the quarter-turn steering wheel is smooth. The steering column tilts and telescopes to your preferred position.
High capacity HVAC
The durable, high capacity HVAC (heating, ventilation, and air conditioning) system provides dependable cooling and heating. Vents in front and on both sides can be directed toward the operator or the windows.
A clean three-piece front windshield and tall, wrap-around rear windows give you a 360˚ view, including the corners of the blade and winch drum. The engine air precleaner has been moved under the hood and the exhaust stack significantly shortened to increase visibility out the front windshield. The engine enclosure and arch and booms are black to reduce glare during night operations.
Other cab features include two large cup holders, one 12-volt power point for cell phone chargers etc., two coat hooks, AM/FM/ CD/Sirius satellite radio package with Bluetooth, USB and auxiliary inputs.
Any commercial DEF that meets the ISO 22241 specification can be used in Cat SCR equipped engines. DEF can be purchased at Cat dealers.
The extended life diesel particulate filter (DPF) was designed for the life of the engine and has a unique remaining life feature which can be checked by your local Cat dealer.
The filter assembly for the pump electronics tank unit (PETU), the tank for onboard DEF storage, must be replaced every 5,000 hours.
The tilting cab with field proven tilting pins provides access to components under the cab. Bolt-on panels around the base of the cab and removable steps provide even more access.
The cross flow configuration and compartmentalization of the engine and cooling system reduce debris collection around the engine, so less time is needed for cleaning. The cooling system pulls external air in the side — not through the engine compartment — and exhausts it on the opposite side.
Smart hose routing
Hoses from the arch to the boom take a lot of abuse from rubbing against the arch and boom of dual function machines. Guarding on the arch and boom protect the hoses. Hoses across the joint are short, so replacement is a low cost fix. Also, stiffness of the Cat XT hoses keep them suspended across the arch and boom joint rather than rubbing against the steel. Center hitch hoses are bulkheaded to optimize serviceability access and durability.
Steering cylinder access
In some skidders, it is not easy to get to the steering cylinders. With the D Series, you just unbolt the cab steps to access the steering cylinders.
The parking brake is normally released hydraulically; however, grease injected from a simple valve near the main control valve will release the parking brake manually if needed.
Grapple head servicing
The new grapple head is designed for greater durability and serviceability. Components and fittings are accessed through the new service panels on both sides of the head and above the grapple tong cylinders.
Other highlights include:
Fuel fill at ground level.
Up to 500-hour engine oil change intervals, pending oil sampling recommendation, keep maintenance costs low.
Electrical harnesses are bulkheaded before entering the cab, improving cab pressurization and reducing dust and noise.
Access to the main control valve is on the rear frame of the skidder.
The engine is serviced at ground level from a single side.
Hinged panels provide access to other daily service points, and hinged belly pans allow water to drain when pressure washing the skidder with the cab tilted.
Large hinged mesh screens over the door windows protect you when the sliding windows are open. They swing out to remove debris.
The D Series skidders come with a machine troubleshooting feature that allows the operator to drill down and pinpoint the root cause of a problem, reducing the need for service calls and holding down costs.
Cat Product Link
Cat Product Link, Caterpillar's machine monitoring system, is standard on all D Series skidders. When installed at the factory, the system comes with a free three-year subscription to VisionLink®, the user interface.
Product Link is an advanced — but user friendly — remote monitoring technology for equipment. With Product Link, you know where your skidder is, what it's doing and how it's performing. Armed with this information you can maximize efficiency and lower operating costs.
Product Link is integrated with the Electronic Control Modules (ECMs) on Cat equipment to collect and deliver valuable information.
Because logging sites tend to be in remote areas, information will be transmitted via satellite for more consistent communications.
You will have remote access to information over the web at any time and any place. With Product Link you can:
Know the location and status of your D Series skidder, including alerts if it is moved without your knowledge
Track fuel use and idle time
Monitor efficiency and health, including fault codes
Access fluid analyses results and online parts ordering
Access model-specific daily safety and maintenance inspection checklists.
Fuel costs. Labor costs. Maintenance costs. They can all tax your patience. But with timely, accurate data, you can better manage your equipment to keep operating expenses in line. Cat® EMSolutions offers everything you need to control costs, help your guys work better, reduce risks and get more done every day.