Gearboxes by family
A gearbox is a housed set of gears, shafts and bearings that changes speed, torque, direction or all three. Industrial gearboxes are usually grouped by how the gears are arranged and how the unit connects to the machine. The detailed comparison of internal gearing designs is covered in the discussion of gear reducer types; this article looks at gearboxes from the application side, asking which family tends to show up where, and why.
Parallel-shaft and in-line helical gearboxes
These are the workhorses of general industry. Helical gears give smooth, efficient power transfer, and stacking stages produces higher ratios. Input and output shafts are parallel or in-line, which makes them easy to fit into straightforward drive layouts. They suit continuous duty, moderate to heavy loads and a wide range of speeds.
Typical applications: belt and chain conveyors, fans, pumps, extruders, and general machinery that runs for long hours.
Right-angle gearboxes
When the driven shaft must sit at 90 degrees to the motor, designers use bevel, helical-bevel or worm gearboxes. Helical-bevel units are generally chosen where efficiency and heavy duty matter, while worm gearboxes appeal when compactness, low noise and a high single-stage ratio are the priority, at the cost of efficiency and more heat.
Typical applications: conveyors where the motor must sit beside the belt, gates and doors, packaging machinery, and drives with tight space.
Worm gearboxes
Worm gearboxes use a worm and wheel. They are compact and quiet and can reach high ratios in one stage. Because of sliding contact they typically generate more heat and lose more energy than helical designs, especially at higher ratios. Some designs resist back-driving, but that behavior should not be relied on to hold a load safely.
Typical applications: light to medium conveyors, hand-fed machinery, rotating tables, and intermittent-duty equipment.
Planetary gearboxes
Planetary gearboxes share load across several planet gears, making them compact for the torque they carry, with input and output on the same axis. They are common in servo systems, travel and slew drives on mobile machinery, and applications where high torque density matters.
Typical applications: robotic axes, packaging machines with precise positioning, winches, and wheel or track drives.
Shaft-mounted gearboxes
A shaft-mounted unit fits directly on the driven shaft and is restrained by a torque arm, so it needs no separate base or coupling on the output side. It is a convenient and economical way to drive a conveyor head pulley or similar shaft, and it is often combined with a belt drive from the motor.
Typical applications: belt conveyor head pulleys, screw conveyors, bucket elevators and similar bulk handling equipment.
Specialized units
Cycloidal gearboxes offer good shock-load tolerance and compact high ratios, and are used where overloads are likely. Harmonic or strain-wave gearboxes give very low backlash in small packages and show up in robotics and precision positioning. Large split-case or heavy-duty industrial units serve mills, kilns, crushers and other heavy applications, often with forced lubrication and cooling.
Matching gearboxes to common applications
Conveyors
Conveyor demands vary with length, incline, belt loading and starting conditions, and the different conveyor types create different needs. Long inclined belts need high starting torque and sometimes controlled starts. Light accumulation lines are less demanding. Shaft-mounted helical units and helical-bevel units are common, with the choice affected by space and duty.
Mixers and agitators
Mixers and industrial agitators usually run continuously at fairly steady torque, but the shaft often carries a significant axial load and bending moment, especially on top-entry vertical designs. Gearboxes for this duty are built with bearings sized for those loads, and variations in fluid thickness can change torque sharply. Sealing against the process and cleaning requirements may drive the housing and lubricant choice.
Hoists and lifting equipment
Lifting duties carry the highest consequences for failure. Designs must meet applicable standards, and a separate brake system and appropriate safety devices are the normal approach; a gearbox should not be assumed to hold a suspended load on its own, even if it resists back-driving. Ratings, inspection and replacement for overhead cranes and hoists follow manufacturer requirements and local regulations, and only qualified personnel should work on them.
Bulk handling
Screw feeders, bucket elevators and rotary valves often use shaft-mounted or in-line helical gearboxes, chosen for continuous duty and tolerance of dust. Seals and breathers matter in dusty settings.
Choosing within a family
Once the family is chosen, details matter: the ratio, the torque and service factor, the mounting arrangement, the environment and the thermal rating. Working through those questions is the heart of gearbox selection, and common ratio terminology appears under gearbox ratios.
Maintenance themes by type
All gearboxes benefit from the same basics: correct lubricant at the right level, clean breathers, sound seals, and attention to temperature, noise and vibration. Differences by type include:
- Worm units: monitor operating temperature and oil condition, since heat is more of an issue and wheel wear is a typical wear mode.
- Helical and bevel units: check for gear tooth wear patterns and bearing noise, along with oil contamination.
- Planetary units: smaller oil volumes mean oil condition matters even more; follow the manufacturer’s interval carefully.
- Shaft-mounted units: inspect torque arm connections and shaft fit regularly.
Details of upkeep, from gearbox lubrication to understanding gearbox failure causes, are covered in other guides. Always isolate and lock out equipment before servicing, following your site procedures and local regulations.
This article is general information, not engineering advice. For any specific machine, rely on the manufacturer’s data and qualified personnel.