When it comes to gearing components, things can get confusing quickly. There are many terms that gear manufacturers as well as engineers and designers use to talk about what sometimes is essentially the same thing. The term "gearbox" is one of those terms, often times used interchangeably with gearhead or gear reducer… even though they sometimes refer to slightly different physical arrangements of gears.
The most basic definition of a gearbox is that it is a contained gear train, or a mechanical unit or component consisting of a series of integrated gears within a housing. In fact, the name itself defines what it is - a box containing gears. In the most basic sense, a gearbox functions like any system of gears; it alters torque and speed between a driving device like a motor and a load.The gears inside of a gearbox can be any one of a number of types from bevel gears and spiral bevel gears to wormgears and others such as planetary gears. The gears are mounted on shafts, which are supported by and rotate via rolling element bearings. The gearbox is a mechanical method of transferring energy from one device to another and is used to increase torque while reducing speed.
Gearboxes are used in many applications including machine tools, industrial equipment, conveyors, and really any rotary motion power transmission application that requires changes to torque and speed requirements.
So it's clear - a gearbox is always a fully integrated mechanical component consisting of a series of mating gears contained in a housing with shafts and bearings (to support and resolve loads) and in many cases a flange for motor mounting. Most of the motion industry makes no differentiation between the terms gearhead and gearbox. But in a few contexts, the term gearbox specifically refers to housed gearing as described above while the more general term gearhead refers to assemblies otherwise open gearing that installs within some existing machine frame. The latter are targeted to compact or battery-powered mobile designs necessitating especially tight integration and omission of extra subcomponents. Here, a series of parallel plates might support the gear-train shafts (and their bearings) and allow bolting to a motor face.
Types Of Gearbox
1. Sliding Mesh Gearbox
It is the simplest type of gearbox. In this gearbox, spur gears are used. The Figure shows the construction of a sliding mesh type transmission having three forward and one reverse speeds. There are three gears attached on the main shaft and four gears on the layshaft. The two gears on the main shaft can be slided by a shafting yoke and mesh with the gears on a layshaft. Therefore, it is called a sliding mesh gearbox. A separate idler gear is mounted on the idler shaft.
2. Constant Mesh Gearbox
Figure shows the construction of a constant mesh type gearbox having three forward and one reverse speeds. In this type of gearbox, all gears are constantly in mesh and dog clutches are used for engaging and disengaging the gears. The dog clutches (D) and D2) are mounted on the main shaft. One (D2) is connected between clutch gear and reverse gear whereas the other (D)) is placed between low speed gear and reverse gear. The splines are provided on the main shaft for the linear movement of dogs. Dog clutch can slide on the shaft and rotate along with it. All gears are rigidly fixed on the counter shaft. All main shaft and layshaft gears, and idler gears are engaged by dog clutch to obtain opposite and slow speed. Only reverse gears are spur gear type and all others are helical gears.
As compared with the sliding mesh type, the constant mesh type gearbox meshes more readily with the gears having less danger of damaging during meshing because the gear diameters are smaller with few numbers of teeth. So, this type has more defects when compared to a synchromesh type. The necessity of double clutching is needed so that it is not used to any large extent.
For sure, there are many kinds of gearboxed for different application, such as Small Car Gearbox, Light Truck Gearbox, Heavy-duty Gearbox, ATV Gear Box, Agricultural Gearbox, Electric Vehicle Gearbox, Motorcycle Gearbox, Electric Vehicle Gearbox, Heavy-duty Gearbox, etc.