Gearboxes
Gear box is an essential equipment in a gear assembly. Gear Box is also
known as Gear head, Gear reducer and Speed reducer. The fundamental
principle of a gearbox is to transmit the cause of mechanical rotation
between two shafts. In this order, there is a structural support present in
between the two shafts. Generally, gearboxes are kept inside the casings.
This helps the gearboxes in their structural support, provides protection
and ensures in doing safe functioning. Normally, the gearboxes are designed
in reducing the speed, but sometimes, a gearbox may be designed for speed
enhancing duties. The shafts inside the gearboxes are placed for the purpose
of accepting and delivering the machinery rotation. This machinery rotation
(torque) is achieved in the form of splines that should be suitable to
connect or join to another unit. The capacity of thrusting outward of the
shafts will have been limited from the casing. The mechanical rotation which
is generated by the engine is consumed through the gearbox. This in turn, is
being converted into a force at the road surface. To accelerate the vehicle,
the force which is being applied can be calculated as follows:
Applied force = Torque at the wheel * radius of the road wheel
(including the tyre)
Types of Gearboxes
There are five types of gear boxes. These five types of gear boxes are as
follows:
- Spur Gear Box
Spur gearbox is an effective and durable mechanical equipment, which is
used for the purpose of transmitting power and uniform and constant
rotatory motion from one parallel shaft to the other shaft. Spur gearbox
is also considered as a capable industrial tool that provides a
continuous speed drive. This speed drive can be increased or decreased
according to the requirement.
- Helical Gear Boxes
Helical gearboxes are quite alike the spur gearboxes in working. These
gearboxes possess teeth that are fitted in a spiral format around the
gear. The modern helical gearboxes are usually designed on a modular
concept of construction and are available in different ratios. These
gearboxes are fabricated to work absolutely without any noise, thus used
in transmission operations.
- Hardened &
Ground Gear Box
Hardened and ground gearboxes are considered one of the best types of
gearboxes in the gears and gearbox manufacturing industry. They are
widely used in many industrial applications in wind mills, cement
industry, agro industry, fertilizer plants, aviation industry, and so.
They are fabricated from industry standard raw materials like nickel,
titanium, and stainless steel.
- Crane Duty Gear Box
These gearboxes are often used in heavy-duty applications. They are one
of the advanced types of gearboxes, which give maximum thermal
efficiency. These gearboxes facilitate the proper meshing of the gear
teeth, which results in enhanced performance of the gear. The high
efficiency is also ensured by its precision gearing and accurate
bearings. It is often used in mining, automobiles, and construction
industry.
- Twin Lobe Blowers
Twin lobe blowers belong to the class of the blowers having positive
displacement. Higher efficiency at moderate compression ratios is the
special feature of these industrial blowers. These blowers are often
used in applications demanding relatively continuous flow rate at
different discharge pressures. The contemporary twin lobe blowers are
available in the capacity range 10m3/hr 10,000m3/hr.
- Gear Box Housings
Gearbox housing is a housing or a kind of cover to accommodate or fit
the gear and gearing equipment like flanges, shafts, bearings, etc.
There are basically two types of such housings available at present in
the market, i.e., cast gearbox housings and fabricated gearbox housings.
Cast housings are made from a process called metal-casting while
fabricated housings are designed in hi-tech machining centers.
- Automatic Gearboxes
For most of the Automatic Gearboxes, there is a selected set of
possible gear ranges. The set selection often have a parking pawl
features. This feature closes the output shaft of the transmission.
Since 1950's, most of the cars which have sold in USA, equipped with
Automatic gearboxes. But, in rest of the world, this trend has not been
followed.
- Semiautomatic
Gearboxes
The semiautomatic Gearboxes are also known as clutch less manual
transmissions or automated manual transmissions, e-gears, or paddle
shift gearboxes. In semiautomatic gear boxes, there are sensors,
processors and actuators. These things help in shifting the gears on the
command of the drivers.
- Manual Gearboxes
The history of manual gearboxes is very old. The traditional clutches
are used in such kind of gearboxes. Each time, these gears are selected
by electrically controlled motors. After the selection, these gears
detach the clutches and the gears are shifted. Once the clutch gets
free, it can be used again.
- Marine Gearboxes
The drive is directly connected to the propeller in a traditional
Marine gearbox. Marine gearboxes fulfill a multiple number of marine
related purposes. To meet each and every purpose, these marine gears do
also have a large number of different configurations and installation
processes.
- Shaft Mounted
Gearboxes
Shaft mounted gearboxes are very closely and firmly design in size.
These gears are directly mounted onto the driven shafts. This mounting
process helps these gears in avoiding the use of coupling and base. In
Shaft Mounted gears, there is no problem in the adjustment. The boxes of
the gears are suitable for both forward and reverse motion.
- Gear Motors
Gears motors are such type of motors which have a large reduction
system. The gearbox is pertained into the motor. This type of integral
arrangement is done in order to increase the mechanical rotational speed
of the motor. But simultaneously, this arrangement reduces the output
speed.
Functions of the Gearbox Casing
- It provides structural support for the shaft bearings. This in turn
helps in gear loading.
- It transfers the reaction of mechanical rotation (torque) to the
other supporting structure of the gearbox or drive elements.
- It prevents the lubricant from spreading and also prevents the
unwanted particals from coming inside.
- It provides the safety provision and reduce the noise intensity.
- It also reduces the amount of heat that generates due to the internal
friction.
- It increases the external and visual qualities of the gearbox.
To obtain the support-rigidity, safety and reliability in operations,
the casings must be located, fitted and fastened properly to their
foundations. Proper provision of ventilation should be ensured in these
casings for removing out the heat which generates during the operations.
Buyers Guide (Selection Process of
Gearboxes)
Before setting out the buying decision of a gearbox, the most important
thing is to ensure about the requirements of the gearbox. The best selection
of a gearbox gives the best outputs in fulfilling the requirements of the
buyers. This kind of successful selection can be achieved by matching the
requirements of the power transmission system with a particular range of
gearboxes offered by the manufacturers. So, it is advisable for the buyers
to have some knowledge regarding the system and available hardwares in the
market. A buyers may do the following things before buying a gearbox:
- Collect informations about the system.
- Review those factors that influence the buying decision.
- Prepare the limit of acceptance and ability of these factors.
- Collect informations from different manufacturers for acquiring
knowledge regarding gearboxes. The entire selection process of a gearbox
can be enlisted through the following flow chart:
Classification of Gearboxes
Today, it is possible to obtain such kind of gearboxes which consist the
characteristics of two or more than two kinds of different gearboxes. These
kinds of gearboxes are called compound gearboxes. The speed ratio in such
kinds of gearboxes is high because the respective speed ratios of each
individual gear box within it are compounded. The classification of
gearboxes is done on the basic of shaft orientation or speed ratio.
Gearing Arrangement for Gearbox
In the gearing arrangement for a gearbox, the various components are:
cycloidal, worm, bevel, planetary, spur and helical.
- Bevel gear is actually a gear wheel that is meshed with another bevel
gear in such a way so that the shafts can form an angle, which is less
than 180».
- Helical gears join shafts that are
parallel. The involute teeth ofthe helical gears are cut at an angle to
the axis of the rotation. If there are two mating helical gears in the
gearing arrangement of the gearbox, then they must have equal helix
angle but opposite hands.
- In case of Spur Gears, they connect
parallel shafts. They have curled teeth which are parallel to the shaft
and may have either external or internal teeth.
- The planetary gears may present in total number of two and they are
present either on or inside a large gear. The intense gear ratio is
possible due to these gears. When the intention is to turn the input in
the same direction of the output, then these gears are used. Planetary
gears can be designed along with a set of planetary cones or with a gear
set.
- Cycloidal gears are used in pair form and they are arranged in such a
way so that the angle formed by them should be equal to180». The
reason behind the formation of 180» is to provide balance to the
load and these gears are driven by many crank shafts. Multiple shafts
are present for sharing the load and to enhance the twisting state
firmness.
- The Worm Gears are wrapped around a
central axle and these have slant plane. This kind of gear consists one
or more than one teeth and these teeth are present in the screwed thread
form.
