In This Article, we will learn about different types of Gears and their uses in various applications. A Gear is a rotating element that has teeth machined on the surface of a solid shaft. When two gears mesh with each other it transmits circular Motion simultaneously altering the speed of Rotation. The working Principles of Gear are there are two types of Gears i.e. Driving Gears and Driven Gears. The Driving Gear gets the rotational Input and Transmits it to driven Gear and thus the whole purpose of the Gearing System is to transmit Rotary motion.
Types Of Gears :-
There are different ways to classify Gears, The most common way is to categorize on the basis of its type. Gears are classified into 3 types; Parallel Axis Gear, Intersecting Axis Gear and Non-Parallel Non Intesecting Acting gear. Spur and Helical come in the category of Parallel axis gears and Bevel gears fall in the category of Intersecting acting Gears.
A simple rolling movement can be observed during the meshing of Paired parallel axis Gears or Intersecting axis gears due to which it has relative minimal slippage and their efficiency is high. On the other hand non parallel and non intersecting gears such as screw gears and Worm gears produce relative slippage while transmitting power as a result friction between two Gears can be observed which causes power losses and indeed the efficiency gets low.
Great efficiency of Gear can be obtained only when the installation is done accurately. Similarly in Bevel gearsets the efficiency will decrease if the mounting of the Gears isn’t done properly that is mounting, off position to the cone-top. In general Theoretical efficiency of these Gears does not include Bearing and lubricating losses.
§ PARALLEL AXIS GEARS
1) SPUR GEAR.
It is a Cylindrical Shaped Gear where the teeth are parallel to the axis of the Gear and it is most commonly used in Planetary Gearsets.
It is linear Rectangular shaped bar on which gears Teeths are machined on the surface of a single side which can mesh with a spur Gear. This is used to convert Rotary Motion into linear Motion.
It is similar to the Spur gear the only difference is the teeths are machined inside a circumferential Ring. It is meshed with a Spur gear for Reduction purpose by rigidly fixing either the Internal gear or the Spur Gear. This Gear is often used in Planetary gear System.
It is a Cylindrical shaped Gear with a teeth formation known as Helicoid Teeth in load bearing comparison. Helical Gears can bear more load than spur Gears and the noise produced while operation is less.
This is Linear shaped Gear that meshes with a Helical Gear. The only difference Between Spur Rack and Helical Rack is Spur Rack has Straight teeth's and Helical Racks teeth are machined at an specific angle.
§ INTERSECTING ACTING GEARS
1)STRAIGHT BEVEL GEAR.
Straight Bevel Gear have Tapered conical Teeths which has the same direction as the pitch cone base line. This Type of Gearset is widely used to transmit motion in the axis perpendicular to each other i.e. 90 degree.
2) ZEROL BEVEL GEAR.
This is a special type of Gearset known as spiral Bevel gear. This Spiral angle in the particular gearset is Zero degree due to which the force acting upon the same.
3) SPIRAL BEVEL GEAR.
This Bevel gears comes with a helical angle of Spiral teeth. It offers higher Strength and low noise.
§ NON PARALLEL AND NON INTERSECTING AXIS GEARS.
1) CYLINDRICAL WORM GEAR PAIR.
Worm Gear pair consist of a worm and a worm wheel meshing with each other which has non parallel and non intersecting axis. The Key feature for worm and worm wheel Gearset is is that we can obtain a very high reduction ratio in a single mesh also it has quiet and smooth motion.
This type of Non Parallel and Non Intersecting cylindrical gear has teeth on one or both side in the form of screw. This type of Gears is used in a combination with screw gear or Spur Gear. This Type assures smooth and quite operation however are not suitable to transmit high power.
GEAR TRAINS :-
Power cannot be transmitted using a single Gear hence atleast two or more than two gears is to be meshed to transmit the motion. This combination of Gears working together is called as gear Train. There are Two Stages in gear Train i.e. Single Stage Gear Train and Two Stage Gear Train.
SINGLE STAGE GEAR TRAIN :-
In a Single Stage Gear train two Gears are meshing with each other to transmit rotary motion simultaneously with reduction of speed.
It is a common case between spur and bevel gear mesh the direction of rotation of driver and driven gear are opposite. On the other hand in case of internal gear mesh both the gears rotate in same direction. In worm mesh the rotation of direction is determine by its helix hand.
TWO-STAGE GEAR TRAIN :-
In two stage gear train two single stage gearsets are combined in a series to get a combined reduction ratio. In this gear train the smaller gear is the driving gear and the largest one is the driven gear. The rotational motion is transmitted through the intermediate gear placed between the driving and the driven gear. The intermediate gear also known as Idler. And if the idler gear and the driven gear has same number of teeth, there is no effect on the speed ratio.
BACKLASH IN GEARS :-
To ensure the smooth rotation of meshed gears backlash is necessary. Backlash is the amount by which a two space exceeds the thickness of a gear tooth engaged while meshing. There are 5 types of backlashes can occur during a gear mesh.
I. Circumferential Backlash.
II. Normal Backlash.
III. Angular Backlash.
IV. Radial Backlash.
V. Axial Backlash.
1) CIRCUMFERENTIAL BACKLASH
It is the length of the arc on a pitch circle. The length is nothing but the distance that the gear is rotating until the meshed tooth flank makes contact while the other mating gear are held stationary.
2) NORMAL BACKLASH
The normal backlash is minimum distance between the meshed tooth in pair of gears when the set so that the tooth surface are in contact.
3) ANGULAR BACKLASH
The maximum angle that allows the gear to move when the other meting gear is held stationary.
4) RADIAL BACKLASH
The radial backlash is the shrinkage in the stated center distance when it is set so the meshed tooth flanks of the paired gears get contact with each other.
5) AXIAL BACKLASH
The axial backlash is the shrinkage in the stated center distance when a pair of bevel gears is set so the meshed tooth flanks of the paired gears contact each other.
METHODS OF REDUCING BACKLASH :-
For High Precision gear Applications, Zero Backlash performance is required So here we will learn about methods of reducing or eliminating Backlash.
1) Use of Gears with Less Tooth Thinning.
2) Control Backlash by Adjustment of the centre distance.
3) Control Backlash by adjustment of the mounting distance.
4) Control Backlash by separating the Gear in two parts.
5) Use of tapered or Spur Gears.
6) Use of Duplex Lead worm gear Pair.
TYPES OF GEAR MATERIALS :-
HEAT TREATMENTS :-
Heat treatment is the process that controls the heating and colling of material to obtain required structural properties. It is performed to enhance the properties of steel as the hardness increases along with tooth surface strength. Heating methods include Normalizing. Annealing, Quenching, Tampering and surface hardening.
It is the Heat Treatment applied to the micro structure of small crystals of the steel to unify the overall structure. It relieves the internal stress occurred by the forming processing such as rolling.
It is a Heat Treatment applied to soften steel to adjust crystalline structure, to relive internal stress or to modify for cold working and cutting performance.
It is a Heat Treatment applied for rapid cooling after heating at heat temperature. Tempering is essential to be applied after Quenching.
Tempering is the heat treatment applied for cooling at a certain speed.Tempering must be performed after Quenching and there are two types of Tempering i.e. High Temperature tempering and Low Temperature Tempering.
5) THERMAL REFINING.
Thermal Refining is the Heat Treatment applied to adjust toughness of steel.This Heat Treatment involves Quenching and High Temperature Temering.
It is a Heat Treatment performed especially to harden the surface in which carbon is present and penetrates the surface.
7) INDUCTION HARDENING.
It is a Heat Treatment performed to harden the surface by induction heating of the steel composed of 0.3% carbon. It is effective for hardening tooth areas including tooth surface and tip.
8) FLAME HARDENING.
It is the surface hardening Treatment performed by flame heating. This treatment is performed on the surface for partial hardening of iron and steel.
Nitriding involves the use of nitrogen into the surface of steel. By using nitriding process hardness can be obtained.
10) TOTAL QUENCHING.
Total quenching is the Heat Treatment by heating the entire steel material to core and then cooling rapidly afterwards where surface and cold part both are hardened.
LUBRICATION OF GEARS:-
Lubrication of Gears is done to avoid difficulties such as tooth wear and premature failure. There are three types of Lubrication Methods in General use; Grease Lubrication, Splash lubrication and Forced Oil Circulation Lubrication and the choice of this lubrication depend upon Tangential Speed and Rotating Speed. Grease Lubrication is good at low speed and for medium and high-speed splash and forced oil lubrication is more appropriate.
Grease Lubrication is suitable for any open or enclosed Gear system but is is not suitable for high load and continuous operation. Splash Lubrication is used with enclosed systems. The Rotating Gear splash lubricant onto the Gear systems and Bearing and lastly the Forced Oil Circulation lubrication applies lubricant to the contact portion of the teeth by the means of oil pump.
There are three types of Methods used for Forced Oil Circulation Lubrication i.e. Drop Method, Spray Method and Oil Mist Method.
WAYS TO REDUCE GEAR NOISE:-
1) Use of High Precision gears.
2) Better Surface finish on gears.
3) Proper amount of Backlash.
4) Ensure Correct Tooth Contact.
5) Increase the Overlap ratio.
6) Use High Rigidity gears.
7) Use of Plastic Gears.
8) Apply Suitable Lubrication.
9) Increase Transverse Contact Ratio.
10) Smooth Meshing.
All the above factors are considered in the Research and Development Procedure of SMD Gearbox due to which SMD can deliver High Precision and High Accuracy Gearboxes suitable according to customer requirements. Because of R&D procedure, the NVH level of the Gearbox can be altered and reduced to avoid fatigue level on workers or employees and hence indeed increase Efficiency and Productivity. Frequent testing of Gears is carried out before assembly like Gear Roller Testing, Noise Inspection, Hardness Testing, Concentricity Testing, Torque Inspection etc. SMD Gearbox is considered to be Best Solution Provider for all types of Servo Gearboxes in the Indian and Global Market. SMD Gearbox are widely used in Automation, Automobile, Pharmaceutical, Aerospace, Engineering, Medical, Agriculture, Machine tool, etc. Industries.