The many gearmotors in warehousing equipment

Today’s automated warehouses are often designed by a small group of mechanical engineers and a veritable army of software engineers — especially where coordination of purpose-built autonomous robot fleets is involved.

Even so, cruise the next MODEX or ProMat show and it will become clear that warehouse equipment relies heavily on electromechanical systems — and especially the noble fractional-horsepower gearmotor. For example, robotics to move product racks or pallets include gearmotors for traversing factory floors, for turning in place, and (in some cases) for lifting transported items — as with a jack screw, for example.

Gearmotors are also found on warehouse conveyors such as accordion-style conveyors and flexible powered conveyors. These are scissor-leg material-handling systems with powered rollers ganged together with round belt at their ends. Often the conveyors move goods through facilities or interface with flatbed shipping trucks at loading docks to hasten loading and unloading. Some accordion-style conveyors are also broken into zones so that conveyed goods are moved along a section at a time.

At loading docks, gearmotors can also power locking restraints that prevent accidents. More specifically, these motorized claw-type dock constraints engage with hardware on trucks to prevent drivers from pulling away when personnel on foot or forklift are still traversing over the area where the backs of trucks interface with the loading docks.

Motorized caster wheels are another place where gearmotors impart motion in warehouses. These wheels in turn install on carts, trollies, and dollies that are meant to move extremely heavy workpieces not easily, ergonomically, or safely moved by manually propelled equipment … especially in settings to support the assembly of big equipment with big and heavy subsystems.

Heavily relying on gearmotors are also man lifts with so-called crow’s-nest buckets in which operators can ride as well as ergonomic workpiece lifts with trolley wheels (sometimes motorized) and a motorized Z-axis platform or end-effectors in the form of pneumatic suction-cup arrays to let operators safely raise and lower items.

Controls: Simple (standalone) to complex (integrated)

A wide variety of controls get paired with these gearmotor-based designs. Most dock restraints are pretty much self‑contained, so operate through a simple on-off switch complemented by a conveniently located emergency-stop button. So too are lift trucks — self‑contained units sans any master control. After all, warehouse personnel operate and steer these vehicles. So for many lift trucks, there’s a just a simple current-limit control (with motor torque directly proportional to current) to command the truck to accelerate, hold speed, and change direction (between forward and reverse).

For such designs, some fractional-horsepower gearmotor suppliers sell simple speed controls with on-off and speed-adjustment functions. However, it’s more common that gearmotors get paired with controls designed by the original equipment manufacturer (OEM). That’s because from a capital-equipment standpoint, it’s easier for an OEM to design their own controls or outsource PC boards to their design. Plus, OEMs typically aim to integrate a given gearmotor’s controls into global control-system functions. So, instead of buying a separate board here and a separate board there, OEMs often design systems so a single board executes all functions.

Reconsider flexible powered conveyors. These include centralized controls that coordinate separate command zones. One long conveyor of this design has a motor (and interconnected controls) every five feet or so — in some cases, flat pancake motors with flat drives. Then switches detect the presence of boxes or workpieces in each zone and activate its motor to carry the items through. Once a zone is cleared of items, it’s automatically turned off and the next zone powered on … and on down the line in a domino effect.

How gearmotors are typically procured

Typically, it’s OEM design engineers or purchasing managers armed with a wish list from the design engineers (and not plant engineers) who interface with suppliers to size and specify components such as gearmotors for standard lifts, conveyors, and other equipment. Distributors and system integrators might then interface with plant engineers to tailor solutions to a given setting. In the past when gearmotors from certain manufacturers have suddenly become unavailable, but OEM designs are already finalized and engineering specs set, purchasing managers have led the hunt for new suppliers.

These insights were gained in a recent conversation with Terry Auchstetter of Bodine Electric Co. For more information, visit bodine-electric.com.

Read more about another warehouse application for gearmotors — in automated guided vehicles (AGVs) — at bodine-electric.com/blog/custom-bldc-gearmotors-for-agvs.