Magtorq Planetary Gear Units detailed in this Catalogue are engineered and manufactured as per the standard recommendations of the American Gear Manufacturers Association (AGMA). Design, Manufacture and Inspection are all acts of engineering, while Application is the art of engineering. Perfection in selection is the basis for successful application. Premature failure of gear systems can be costly and one common reason for failure can be a simple omission at the time of selection. The transmitted power and torque, the inputspeed and the reduction ratio form the base for the selecting a suitable gearbox for any given application. But the minute details such as orientation, load pattern, duty-cycle, environment, over-hung loads, thrust-loads, reliability, life, lubrication, accessibility, ease of maintenance etc. influence the performance of a gearbox considerably and all these need to be taken into account to complete the art of selection.
We hope that the information and guidelines provided within these few pages will help you in selecting the Magtorq gear unit most suited for your application. For requirements and service conditions not mentioned in these pages please contact us so that we may give you further assistance in selection. In any case it is recommended that your selection be counter-checked and confirmed by our application engineers.
Salient Features
High torque to weight ratio - Single piece design concept for annulus-housing configuration results in at least 200% increase in torque to weight ratio of MAGTORQ GH Series planetary gearheads, and hence lower inertia as compared to the conventional gearheads.
Low Backlash - Backlash-free operation is ideally desirable in automation. While the total elimination of backlash is practically impossible in toothed gear transmissions, it is possible to reduce backlash to a minimum through close control of the dimensions of the gear teeth. MAGTORQ GH Series planetary gearheads are specified for backlash of better than 10 arcmin. for standard models and better than 5 arcmin. for precision class models.
High cyclic load carrying capacity - MAGTORQ GH Series planetary gearheads are designed to deliver the rated acceleration torque upto 900 cycles per hour. For more frequent cycles or for applications having frequent reversals of direction of rotation, de-rating of the gearheads is recommended.
High peak torque capacity - MAGTORQ GH Series planetary gearheads are designed to withstand the rated peak torque for maximum 1000 cycles during their service life. For applications needing higher cycles of peak torque higher frame size is required to be selected.
High Torsional Stiffness - Faster accelerations & decelerations , changing speeds, large number of start-stops & reversals, etc, which are typical requirements of most of the servo systems, give rise to undesirable oscillations in drive & driven mechanisms affecting the positional accuracies. High torsional stiffness of the drive mechanism reduces such undesirable oscillations.
MAGTORQ GH Series planetary gearheads have larger shafts, and unique gear teeth design with tight tolerances for obtaining higher torsional stiffness than equivalent standard gear reducers.
Precise Positioning - Lower backlash and higher torsional stiffness of MAGTORQ GH series planetary gearheads make them suitable for applications requiring precise positioning.
Long-life Lubrication - MAGTORQ GH Series planetary gearheads come with factory-filled synthetic lubricant for longer service life, eliminating frequent re-lubrications and completely avoids messy oil leakages. Planetary configuration, an inherently balanced system, automatically redistributes the lubricant to all the gear meshes and bearings.
Easy Motor Mounting - Self-supported hollow input shaft and tailor-made input flange enable direct mounting of specific motor on the gearhead, eliminating need of external coupling.
Square shaped Body & Mounting Flanges - MAGTORQ GH Series planetary gearheads come with square shaped housing for easy and esthetic fitment of the square shaped servomotors.
Quiet operation - Ground and profile corrected gears reduce the noise level of MAGTORQ GH Series planetary gearheads to below 72dB under normal running conditions.
High radial load carrying capacity - Use of larger diameter output shaft & its bearings, wider bearing span through straddle mounting of the output member, etc., enhances the radial load carrying capacity of MAGTORQ GH Series planetary gearheads by over 300% as compared to conventional gearheads.
Selection Procedure
Following points give the general guidelines for the selection of MAGTORQ GH Series planetary gearheads on the basis of the dimensions and performance characteristics of the servo motors that are being used with them. Please refer to the performance data table and proceed as detailed below.
1. Motor Dimensions : Check motor's mounting flange PCD and select GH Series Gearhead of equal or higher PCD. In case of square shaped servo motor, check the square dimensions of the servo motor & select the GH Series Gearhead having equal or next higher frame size. For example servomotor having square dimensions upto 90mm sq. MAGTORQ Gearhead model GH90 can be used, which has 90 mm sq. body dimensions.
2. Reduction Ratio : Select the reduction ratio that is required for the above table. MAGTORQ GH series gearheads are rated for the maximum input speed of 3000RPM. For optimum size of the servomotor it is recommended to select the gearhead having reduction ratio such that maximum speed of the servomotor matches with that of maximum speed required at the driven mechanism.
3. Input torque : Check maximum acceleration torque of the servo motor, multiply this torque rating with the required reduction ratio to get the maximum acceleration torque available at the output of the gearhead, this should be less than the maximum acceleration torque rating, Ta, of the selected gearhead.
Ta can be applied for maximum 900 times per hour. Select higher frame size of the gearhead if Ta does not meet the demand accelerating torque requirement. Larger frame size may also be required if application demands duty cycles of more than 900 per hour.
4. Peak torque : The peak output torque rating, Tp, indicates the capacity of the gearhead to withstand the short time load transients that result from instantaneous stoppage of the servomotor by applying its emergency stop brake, jamming of the driven mechanism, etc. Tp can be applied for maximum of 1000 times in service life of the gearhead.
5. Thermal Rating : Thermal rating is the power that can be transmitted by the gearhead without exceeding the permissible temperature rise. Check the thermal rating (Watts) of the selected gearhead to ensure that it is within the average power (Watts) that the application demands. Performance data table gives the thermal ratings of these gearheads at ambient of 40 deg C. as well as at 20 deg. C. Select the higher frame size if demand average power exceeds the specified thermal rating of the gearhead.
Bevel - Planetary Gear Reducers for High Torque Applications.
Yaw Gearmotors for Wind Power Generators.
Gear Units for Decanter Centrifuges.
Wheel, Track and Crawler Drives for Mobile Equipment.
Drives for Cranes and Hoists.
High Precision Azimuth and Elevation Drive for Antennae.
Differential Units for Transmission of Hoist Mechanisms.
Drum Gears for Belt Conveyor Drives.
Compound Planetary Units.
High Speed Turbine Drives.
About Planetary Gearheads
MAGTORQ introduces a wide range of GH series precision planetary gearheads for motion and position control mechanisms for industrial automation systems, robotics, machine tools, medical equipments, packaging machines, and host of other applications requiring high performance servo drive systems.
Designed by our own R&D team, development of GH series precision planetary gearheads is a result of our decade long experience in manufacturing variety of planetary gear reducers, and customized gear transmissions for demanding & critical applications in Material Handling Equipment, Mining, Sugar, Paper, Steel, Power Plants, Wind Mills, Defence, Pharmaceuticals, etc.
Servo drive system demands fast dynamic response, changing speeds, precise position & motion control, large number of starts / stops, and high torque to weight ratio components. MAGTORQ precision planetary gearheads are designed to meet these demanding requirements. With 8 Frame sizes to choose from and each frame size having 15 gear ratios, from 4:1 to 125:1, MAGTORQ GH series meets the requirements of the most of the general purpose servo applications.
Rating
The ratings of the units indicated in this catalogue represent the mechanical capacity of the gears and unit components for a service factor of 1.0 with respect to pitting and bending strength peak loading not exceeding the following conditions-:
Not more than four peaks per eight hour working period.
Time duration of each peak shall not exceed five seconds.
Each peak shall not exceed 200 % of the catalogue rating.
Operating speed
The maximum operating speed of all the gear units specified in this catalogue is restricted by the factors such as pitch line velocity, lubrication, churning losses, bearing life & limiting speed of bearings. For operating speeds higher than those indicated, please seek our confirmation.
Service Factors & Rating
The service rating of a Gearboxe represents its capacity to meet the specific requirements of the actual applications, considering the operating conditions the desired service life and reliability. At the first estimate service rating multiplied by an appropriate service factor shall not exceed the catalogue rating. This factor measures the intangibles such as load variations, shock and overloading, Reliability and Life. The service factors listed in Table 1 are based on the experience of gear manufacturers and users over the past several years. They have served the industry well, and can be used with a good deal of confidence if the application has been idetified by knowledgeble and experienced gear design and application engineers. It may be noted that the tabulated values apply only to a speed reducing gear box, with a uniform torque input as is the case when driven by electric or oil hydraulic motors or steam or gas turbines.
For speed increasing applications or when the input torque varies cyclically (i, e, engine drive), please refer back to us.
SERVICE FACTORS FOR ENCLOSED GEAR DRIVES, DRIVEN BY MOTORS (HYDRAULIC & ELECTRIC) AND TURBINES (STEAM OR GAS)
Application
Load duration/day
Application
Load duration/day
Upto 3 Hrs
3 to 10 Hrs
Over 10 Hrs
Upto 3 Hrs
3 to 10 Hrs
Over 10 Hrs
AGITATORS (Mixers)
* CRANES – Dry Dock
Pure Liquids
1.00
1.00
1.25
Main Hoist
2.50
2.50
2.50
Liquids and Solids
1.00
1.25
1.50
Auxiliary Hoist
2.50
2.50
3.00
External Influencing Factors
Several external factors affect the performance of a gearbox and need to be considered in the selection process. These external factors can be broadly classified as
Overhung loads
Thrust loads
Ambient temperature and environmental conditions.
Overhung Loads
Overhung loads act on the shaft extensions when belt pulleys, chain sprockets or gears/ pinions are mounted on them to transmit power. Misalignment between two connecting shafts can also give rise to overhung loads. Overhung loads on shafts result in bending moments and additional radial loads on the supporting bearings.
The effects of overhung loads on the gearbox elements can be reduced by
Use pulley, sprocket, pinion etc. of the largest possible diameter and locate them as close to the shaft collar as possible.
When belt transmission is used, the belt tensions should be maintained just sufficient to ensure operation without slippage.
Overhung loads will be minimum when the power transmission is through:
Direct coupling with capacity to adjust itself for minor shaft misalignments i.e. through Gear couplings, flexible couplings etc.
Spline connections to shafts which are well located
The effects of Overhang loads on the gear box elements can be reduced by
Locating the pulley, Sprocket, Pinion etc. as close to the shaft collar as possible. Special protection can be provided on request.
Belt tension should be just sufficient to ensure operation without slippage.
Excessive belt tension will only increase the overhand loads.
Allowable Overhung loads on output shafts based on L10 bearing life of 5000 Hrs. for each size are listed in Table below.
Calculation :
Allowable over hang load at any point can be calculated by the following formula
Over hang load at any point (fra):-
Fra = Frc . Frm . x / (Frm . x + (Frc – Frm) (x+y))
Where,
Frc – overhang load at shaft collar Frm – over hang load at shaft middle x – distance between shaft collar to shaft middle y – distance from shaft middle (y is +ve towards shaft end & y is –ve towards shaft collar )
Bearings
Input shaft bearings
Input shaft bearings are selected without considering external radial/axial loads or moments. Please consult factory for advice in case the input shaft is subjected to external loads.
Planet bearings All planet gear bearings are selected for L10 life of 5000 hrs. assuming an input speed of 1500 rpm to the gear box. When a gear unit is selected with service factor, the bearing life also increases and hence use the following formula to get the adjusted bearing life.
Output shaft bearings
Output shaft bearings are selected for a minimum L10 bearing life of 5000 hrs for the allowable overhang load listed with reference rpm (Nr) at 300 for S-Series, 80 rpm for D-Series, 20 rpm for T-Series and 5 rpm for Q-Series gear units.
For calculating the actual bearing life:
L10a = 5000 (Fra/Fr)3 (Nr/Na)
Where :
Fra = Allowable radial load Fr = Applied Radial Load Nr = Reference rpm Na = Actual rpm
Typical Selection
The preliminary selection of an unit can be made from the power ratings specified in the selection chart . Once the preliminary selection has been made the external influencing factors must be taken into consideration. Torque demanded by the application should not exceed the limits specified.
In the case of an electric motor of 4P / 6P / 8P the unit rated for the input speed and the torque can be directly selected from the selection table. The next step is to consider the service factors demanded by the application. Refer table of service factors for the same. Then the unit selected should satisfy the following relation.
Pin . Sf < Pr.
Where
Pin = Input power in kW Sf = The service factor selected. Pr. = The rated power of the unit
In the case of a hydraulic motor the following formula may be used to determine the input torque (Tin).
Tin = V . p . h m Nm 20 p
where
V = Displacement of the hydraulic motor in cc/rev. p = Pressure in bar. h m = Hydraulic motor efficiency
The following formulae may be used to calculate the Output torque.
Tout = Tin . i . h Nm
Where
Tout = Maximum torque at the output. i = Reduction ratio of the gear unit. h = efficiency of the gear reducer (98% per stage of reduction)
For selecting an ideal gear unit the following relation should be satisfied.
Tr > Tout . Sf.
Tr = Rated output torque of selected gear unit in Nm
J. K. Industrial Corporation Manufacturing and exporting lawn mowers such as garden lawn mowers, manual lawn mowers, roller type lawn mowers, grass cutting lawn mowers, hand operated lawn mowers, commercial lawn mowers and customized lawn mowers.
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