There are two ways to mount a gear drive into a system – foot-mounted or shaft-mounted. Like shaft arrangement, mounting is determined by the space and structure limitations in the system. Foot-mounted gear drives are mounted to a foundation or baseplate through bolt holes in their feet. That may seem simple, but it requires that the foundation is sufficiently rigid to support the drive and the torque passing through it. These drives are sensitive to soft-foot, a condition that occurs when the feet aren’t level to each other which causes misalignments between the shafts. Foot mounted drives should also be on foundations that are well connected to the motor and driven equipment foundations. This prevents the equipment from moving independent of each other, which also causes misalignment and vibration.
If it’s not possible to place a foundation for the motor, gear drive, and driven equipment into the application, the gear drive may be shaft-mounted to the application. In this case, the gear drive low speed shaft is rigidly connected to the driven equipment shaft. This can be done by making the low speed shaft of the gear drive hollow and securing it in place around the solid shaft of the drive equipment with a bushing and keeper plate. It can also be done with a rigid flange coupling that connects the sold shafts of the gear drive and driven equipment together.
When a gear drive is shaft-mounted, it hangs in space by the low speed shaft connection. The motor can be direct coupled to the gear drive via an adapter, a scoop mount, or a swing base. It can also be mounted on top of or next to the reducer via belts or chains. The gear drive and motor system will want to rotate about the gear drive’s low speed shaft, so a torque arm is required to bolt into some structure and prevent rotation.
Over time, the term “shaft-mount” has become nearly synonymous with relatively small gear drives that are designed without feet for light conveying applications. When selecting and sizing a gear drive, keep in mind that the orientation of the shafts and the type of mounting must both be used to fully specify the gear drive!