Sensors Position Swing-Reach Lift Truck for Sideway Operation

Most people are familiar with the front-facing load-bearing forks found on standard forklifts or lift trucks. Under normal operation, the truck driver swings the forklift to face the material to be moved, then drives forward to place the forks into the lift area of the pallet. This means, of course, that the aisle where the forklift operates must be wide enough to handle the overall length of the truck from the tip of the forks to the rear bumper. This minimum-aisle-width limits the number of shelves in the warehouse or storage area. Reducing aisle width permits installing additional storage shelves, boosting warehouse capacity and efficiency.

Raymond Corp.’s (Greene, N.Y.) 9000 Series Swing-Reach lift truck lets warehouse designers shrink aisle widths with forks that turn side-facing or front-facing. This lets operators work in less aisle space — as little as 66-in. wide — because the truck never has to face the material it moves.

While the Swing-Reach truck has been manufactured for decades, the 9000 Series has a number of industry firsts. These include extending battery life by recovering energy as the load is lowered, accurate lift positioning, and user-optimized travel speed and acceleration. These advances contribute to greater operator productivity and safety. Pallets move down narrow aisles, then up 45 ft, while the acceleration, maximum speed, and deceleration of travel, lift, lower, and load handler are programmed to the truck driver’s personal skill level and other factors.

Motion control becomes a critical task when moving a 3,000-lb load. The design of the 9000 Series centers around Raymond’s Intellispeed control and ACR system. Intellispeed coordinates multiple-axes travel speeds based on load weight and height, while ACR provides quick acceleration, smooths lift-and-lower speeds, and smooths direction changes.

Central to the load-moving motion is the mast that the lifting forks move along vertically. Raymond calls this the mini-mast. The mini-mast is part of the system that lets operators move loads up, down, and side-to-side at lateral speeds up to eight inches per second. It uses hydraulic cylinders and steel rails attached to lift forks to move loads. Tracking the position of the mini-mast is key to efficiently and repeatedly performing material handling tasks.

Raymond engineer Dan Driscall describes the motion control aspects of the 9000 Series, “The truck is a Swing-Reach truck with a mast and set of forks. This system swivels and travels back and forth. It is especially important to know the center crossing and approaches to end points for stability reasons. The mast and forks move via a rack-and-pinion steering setup making a multiturn measurement necessary. Velocity is also important to know.”

Additional position sensor specifications included absolute-position sensing to monitor mast position, noncontact technology for long life, and have the ability to count up to 12 turns. The search led the Raymond engineers to Novotechnik in Southborough, Mass., and its recently launched RSM2800 Series of multiturn angle sensors.