2017 International Forest Industries Magazines IFI Aug Sept 2017 v2 | Page 67

Cat D Series wheel skidders
enable loggers to operate more
profitably by getting to the landing
faster, increasing production,
and reducing operating costs.
In addition, a new rotating seat
combined with innovative seat
suspension technology provide
unmatched comfort for operators
and help improve the bottom line
for logging contractors.
Cat D Series skidders feature
a six-speed transmission with
more gears in the working zone,
lock-up torque converter and
independent front and rear
differentials for more pulling power
and control, high-capacity cooling
system and reversing fan, and
high-performance hydraulics. The
machines offer a roomy, quiet, and
cool operator station and tilting
cab for servicing. Four models
range from the Cat 525D (203 hp,
151kW) to the Cat 555D (275 hp,
205kW).
“Loggers have a more versatile
machine that is highly effective
in sensitive applications such as
first thinnings while maintaining
the stability for working in tough
conditions,” said Matt McDonald,
product specialist for Caterpillar
Forest Products.
While faster, more powerful,
and more versatile, Cat D Series
wheel skidders are more efficient,
too, reducing operating costs
to loggers. For example, fuel
economy and total fluid efficiency
is improved, and extended service
intervals reduce maintenance.
Caterpillar began offering the
High Rotation Seat cab and an
enhanced monitor display for Cat
D Series wheel skidders earlier
this year. The High Rotation Seat
cab provides 100 degrees of seat
rotation and features the new
Cat Advanced Ride Management
(Cat ARM) seat suspension for
enhanced ergonomics and comfort
for the operator.
The Cat Advanced Ride
Management (Cat ARM) seat
suspension system features a
breakthrough technology. The
semi-active suspension dampens
vibration – adjusting in real time
to changing ground conditions –
and minimizes end stop events.
The result is significantly and
measurably improved operator
comfort. The operator is stabilized
and experiences a smoother ride,
reducing fatigue.
Cat ARM allows operators
to remain in the machine for
longer periods of time. Increased
utilization of the skidder increases
revenue and profit potential,
particularly in the case of long
skids when return speed and cycle
times are critical. Skid distances
potentially can be extended,
minimizing operating costs for
the job site. Another benefit is
that high-ply rated tyres may be
considered to potentially improve
tire life while maintaining a
smoother ride for the operator.
A key safety advantage of
the Cat High Rotation Seat is the
utilization of the park brake to hold
the machine in place when the
operator is rotating the seat. The
park brake will automatically apply
when the seat is released.
“Because we use the park brake
to hold the machine in place when
the operator rotates the seat, the
skidder will not ‘creep’ even if it
is on a slope,” said McDonald. “It
enhances safety.”
Combined with the integrated
Cat ARM seat suspension,
four-point seat belt and joystick
steering, the High Rotation Seat
reduces operator fatigue and
provides leading ride quality for
the operator. “Ride quality for the
operator is best in class,” said
McDonald.
Cat D Series skidders are
equipped with the Cat C7.1 ACERT
engine. It delivers more power
and more fuel economy while
complying with both U.S. EPA Tier
4 Final and EU Stage IV emission
standards. The D Series also offers
a Cat C7.1 ACERT engine that is
equivalent to US EPA Tier 3 and EU
Stage III emission standards.
The high-capacity cooling
system and on-demand,
hydraulically driven reversing
fan keep the engine running at
proper operating temperature,
optimizing performance,
durability and fuel efficiency.
The cross-flow configuration
and compartmentalization of
the engine and cooling system
maximize efficiency and reduce
debris collection. Cool ambient air
The Cat 555D is a more efficient unit than its predecessors
The Cat 535D skidder
is pulled in from the side – not from
the engine compartm ent – and
air is exhausted out the opposite
side. The oversized fan spins only
as fast as needed to maintain
proper operating temperature, and
it automatically reverses every 20
minutes to expel debris.
The torque converter enables
a smooth start when the skidder
has a heavy load. Then the lock-up
clutch automatically engages, and
the transmission goes into direct
drive for high efficiency hauling. 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 and
manoeuvrability. The locks are
hydraulically actuated and can be
engaged on the go.
A new hydraulic system gives
Cat D Series skidders faster multi-
functioning capability and greater
lift capacity. “You can steer, back
up and activate arch, boom and
grapple functions at the same
time,” said McDonald. “Cycle times
are significantly faster, increasing
productivity.”
Increased rigidity of the lower
frame gives extra support to
the bottom guarding to prevent
damage from stumps and rocks.
The rear frame, which has to stand
up to heavy, swinging and twisting
loads, features box-section
construction. The 360° continuous
rotation grapple features box-
section construction and threaded
grapple tong pins that maximize
structural integrity.
International Forest Industries | AUGUST / SEPTEMBER 2017 65