Turret Truck

Overview

A turret truck is a very-narrow-aisle (VNA) forklift built to work in warehouse aisles only slightly wider than a loaded pallet. An ordinary counterbalance truck has to turn its whole body to face a rack, which needs a wide aisle. A turret truck does not turn. Instead the forks sit on a Turret Head that rotates about 180 degrees and shifts sideways, so the truck stays centered in the aisle and presents the load to either the left or right rack. Packing aisles this tight lets a warehouse store far more pallets in the same floor area, which is the whole economic reason these trucks exist.

The machine is built around a Chassis that carries the Traction Battery low and to the rear as a counterweight, a tall Mast Assembly that lifts the load and, on a man-up truck, the operator with it, the swing-reach Turret Head that handles the pallet, a Traction Drive Unit for travel and steering, a Hydraulic Power Unit for all the rams, a Guidance System that keeps the truck tracking the aisle, a Control System that coordinates everything over CAN, the Operator Cab, and a Safety System.

Chassis and battery

The Main Frame is a heavy welded steel weldment with a narrow footprint and a deep, low battery well. The Battery Bay is a side-extraction compartment: the battery sits on a Battery Roller Floor floor behind a Battery Door held by a Battery Latch, so a depleted pack can roll out sideways and a charged one roll in without lifting. The Traction Battery itself is a Li-ion array of Li-ion Cell, 21700 cells in a Battery Tray, watched by a Battery Management Board. Its mass is deliberate. It ballasts the truck against the forward moment of a raised load. The Mast Mount transfers mast loads into the frame through a slewing bearing, and bolt-on Skirt Panel covers give service access.

Mast and turret head

The Mast Assembly is a three-stage telescopic mast. Nested Mast Stage Rail rails slide on Mast Roller guide rollers, the Lift Cylinder extends the stages, and a Free-Lift Cylinder raises the Lift Carriage on its own before the mast itself begins to telescope, which helps under low ceilings. A pair of Lift Chain leaf chains run over sheaves to lift the carriage. The carriage carries the Cab Platform so the operator rises to the pick face.

The Turret Head is what makes the truck a turret truck. A Rotation Drive uses a Servo Motor and the Rotation Gearbox to swing the fork carriage on the Slewing Bearing. A Traverse Slide, riding on Linear Guide Rail rails and driven by the Traverse Cylinder, shifts the forks sideways to clear the rack upright before a pallet goes in. A Fork Tilt Mechanism mechanism with the Tilt Cylinder sets the fork angle, and the Fork Pair carries two forged Fork tines.

Travel, steering, and hydraulics

The Traction Drive Unit is a combined drive and steer module. A Traction Motor drives the Drive Wheel through the Drive Gearbox, a Steer Motor swings that wheel to steer, and a Service Brake holds the truck. Two Load Wheel rollers support the front. Hydraulic power comes from the Hydraulic Power Unit, where a Pump Motor drives the Gear Pump, and the Valve Bank of proportional Proportional Solenoid Valve cartridges meters flow from the Hydraulic Tank to lift, tilt, rotate, and traverse functions.

Guidance and control

In a VNA aisle the operator cannot steer accurately enough by hand at height, so the Guidance System takes over. With wire guidance a Wire Guidance Antenna senses a buried floor wire through its Antenna Pickup Coil pickups and feeds the Guidance Controller, which steers the truck down the centerline. Rail-guided aisles use Rail Guide Roller rollers that bear on guide rails instead. A Rack Position Scanner reads barcode labels to confirm the target slot. The Control System ties it together: a Traction Inverter and a Pump Inverter drive the motors, and the Vehicle Controller, built on a Compute SoC Module, runs the CAN network and sequences turret motion so the forks only rotate and traverse when the truck is correctly positioned.

Operator cab and safety

On a man-up truck the Operator Cab rises with the load. The operator works from a Operator Seat, commands travel and hydraulics through two Control Joystick controls, and reads height, weight, and slot data on the Operator Display. A Overhead Guard protects against falling stock. The Safety System adds a Emergency Stop, a End-of-Aisle Sensor that slows the truck near aisle ends, a Lift Height Encoder for lift limits, and Warning Light beacons.

How it works in use

The operator drives into a guided aisle and the guidance system locks the truck to the centerline. At the target bay the mast lifts, on a man-up truck carrying the operator to the pick face, the scanner confirms the slot, then the turret head rotates the forks toward the correct side, traverses out to clear the upright, and sets the pallet down. Because the body never turns, the same truck serves both sides of an aisle barely wider than the pallet, which is how a VNA layout reaches its high storage density.

Materials and variants

Structural parts are welded and cast steel for stiffness under high reach. Wheels use polyurethane tread for hard warehouse floors. Man-down variants keep the cab fixed at floor level and only raise the forks, trading visibility at height for lower cost. Wire guidance suits retrofits while rail guidance suits new builds. Lift heights and capacities scale with mast stages and counterweight battery mass.