Reach Stacker Product

Overview

The reach stacker is a mobile craned container handler designed for high-stacking operations in container terminals, inland depots, and consolidation facilities. Unlike straddle carriers that straddle the load, the reach stacker uses a long articulating boom with a telescopic extension and dual-cylinder spreader carriage to stack containers 5–6 tiers high. The boom extends outward from the tractor frame, allowing the operator to place containers on distant stack rows without repositioning the chassis multiple times.

Reach stackers are the workhorse equipment in modern container yards, offering superior reach and stacking height compared to straddle carriers while maintaining better fuel efficiency than large gantry cranes. The combination of telescopic boom extension, load-sensing proportional hydraulics, and a heavy counterweight frame enables precise, rapid container positioning with minimal yard congestion.

How It Works

The reach stacker begins each operation with the diesel engine warm and idle, the boom tilted fully rearward, and the spreader carriage retracted at boom tip. The operator steers the tractor to position the machine perpendicular to the container target using the Steering System. The Steering Wheel commands the Steering Cylinders to articulate the Front Steering Axle kingpin.

Once positioned, the operator uses the Control Panel with proportional joysticks to lower the spreader carriage by retracting the Tilt Cylinder. The Spreader Carriage descends vertically until the Twist-Lock Mechanisms engage the container corner castings. Motorized lock actuators twist each corner 90 degrees to secure the load. The operator monitors the Load Cell reading on the cab display to confirm full engagement.

With the container locked, the operator raises the spreader by extending the Tilt Cylinder, lifting the container clear of the ground or lower stack. The Boom Sections remain at neutral extension during this phase. Once clear, the operator engages boom extension via the Boom Sections telescopic cylinders, pulling the container outward toward the target stack row. The Slew Drive Motor rotates the boom up to 90 degrees from its initial axis.

The tractor advances slowly forward as the operator tilts the boom forward (pitching downward) to position the container above the target location. Fine adjustments to boom extension and tilt are made via load-sensing proportional pressure from the Main Hydraulic Pump, which senses the load weight and modulates pump displacement to provide exactly the pressure needed—no excess, no starvation.

Once positioned, the spreader carriage Lift Cylinders extend, raising the container vertically above the stack, then retract to lower the container onto the support structure. The twist-locks automatically release, and the operator retracts the boom, withdraws the tractor, and returns to the next container.

Subsystems

Chassis and Frame

The Chassis is a heavy-duty tractor base with Main Frame, Engine Mount, Boom Pedestal, and Counterweight Mount. The frame is welded steel box-section with reinforced cross-members. The Boom Pedestal is a large casting welded to the frame, serving as the pivot point for boom tilt and slew. The Counterweight Mount is a cantilevered bracket extending behind the rear axle, anchoring 12–20 tonnes of Counterweight Blocks to balance the lifted load moment.

Boom System

The Boom System is the machine's defining feature. The Boom Sections are three nested steel tubes with roller bearings and wipers. The inner section is fixed to the slew ring; the middle and outer sections telescope hydraulically. The Tilt Cylinder (dual cylinders for even lift) raises and lowers the entire boom structure vertically. The Slew Drive Motor is a radial piston motor with integral slew ring bearing, enabling 180+ degree rotation of the boom in both directions. The Boom Hydraulic Hoses are routed through the boom interior with swivel joints at each telescopic junction, and load-sensing Pressure Sensor feeds load weight to the control system. The Encoder on the boom tracks extension position for operator feedback.

Spreader Carriage

The Spreader Carriage is mounted at the boom tip. It comprises a light Spreader Frame, dual Lift Cylinders (6–10cm bore), four motorized Twist-Lock Mechanisms, and a Load Cell measuring container mass. The lift cylinders raise and lower the carriage vertically relative to the boom tip, independent of boom tilt.

Power and Drivetrain

The Diesel Engine is a turbocharged 6-cylinder or 4-cylinder producing 250–350 kW. The Engine Block, Fuel Tank, Cooling System, and Air Intake System complete the engine subsystem. Power flows through the Drivetrain: a Torque Converter smoothly couples the engine to the Transmission (typically 3–4 speed automatic), which drives the Rear Drive Axle and Front Steering Axle. The rear axle provides traction; the front axle carries load and steers.

Steering

The Steering System is fully hydraulic and power-assisted. The operator turns the Steering Wheel, which modulates the Steering Valve. A dedicated Steering Pump supplies low-pressure steering flow to dual Steering Cylinders that push and pull the front axle kingpin. Turning radius is tight—typically 6–8 meters outside edge—enabling the machine to maneuver in confined terminal spaces.

Operator Cab

The Operator Cab is a fully enclosed, climate-controlled enclosure mounted on the frame. The Cab Frame is welded steel tubing with rubber isolation mounts. Large Side Windows provide 360-degree visibility, and an Overhead Mirror mounted above the cab aids in visualizing the boom and spreader at full height. The Seat Assembly is an air-suspended operator seat with proportional control joysticks integrated into the armrest. The Control Panel displays engine speed, load weight, boom extension percentage, system pressure, fuel level, and coolant temperature. The Climate Control Unit maintains comfortable operating temperature year-round.

Hydraulic System

The Hydraulic System is the control and power backbone. The Main Hydraulic Pump is a variable-displacement pump with load-sensing compensator that automatically reduces flow when demand drops, improving fuel efficiency. The pump senses load pressure through the Proportional Control Section section and modulates displacement to maintain a constant 20–30 bar margin above the highest-load function. This load-sensing design allows smooth, responsive control without heat generation.

The Proportional Control Section is a multi-section proportional spool valve with independent spools for boom extend, boom tilt, boom slew, and spreader lift. Each spool is controlled by an electrical proportional solenoid responding to joystick input from the cab.

The Pressure Relief Valve opens at 280 bar to protect the system from overpressure. Two Accumulator units (bladder accumulators, 20–40 liters each) absorb shock loads when rapid movements occur, protecting hoses and seals.

The Hydraulic Reservoir holds 800–1200 liters of ISO VG 46 fluid and includes a large return filter (10 micron), suction strainer, and baffle plates promoting settling and heat rejection. The Hose and Line Distribution network includes SAE-rated hoses with ISO-port quick-connect couplers, and manifold blocks consolidate valve connections and reduce leak points.

Performance and Operational Characteristics

Reach stackers are typically deployed in clusters of 3–6 units per terminal, enabling multiple stacking sequences in parallel. Fuel consumption under typical yard duty (50% loaded, 50% empty travel) averages 35–50 liters per hour. Modern machines integrate telematics, load weighing, and fleet management systems that track utilization and predict maintenance intervals.

The heavy counterweight (12–20 tonnes) allows high-reach stacking but requires robust wheel assemblies and multiple axles to distribute weight on ground. Tire life is typically 3,000–5,000 operating hours. Hydraulic maintenance—filter and fluid changes—occurs every 1,000–1,500 hours. The load-sensing proportional system reduces heat generation and extends oil life compared to non-proportional systems.

Safety features include load-limiting devices (preventing over-lift if container mass exceeds rated capacity), boom angle sensors feeding data to the control system, and operator training on safe stacking sequences and rollover prevention in high winds or sloped terrain. Modern ISO 19289 certification ensures that reach stackers meet international lifting and handling safety standards.