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RA
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RA

Product catalog summary
Overview: This document is a technical catalog for Nabtesco's Precision Reduction Gear RV TM, focusing on the RA Series high precision gearhead. It covers product specifications, applications, operational principles, warranty details, and contact information.
Specifications: The RA Series gearheads are designed for high precision control in applications such as ATC magazines, ATC arms, APC, and turret drives of lathe machining centers. They feature high reliability, rigidity, precision, and torque, with capabilities to handle high shock loads, high torsional rigidity, and minimal backlash.
Applications: Nabtesco's technologies are utilized in various fields including construction machinery, bullet trains, airplanes, tankers, wind turbines, and robots. The RA Series is specifically used in machining centers and NC lathes for tasks like ATC magazine drives and lathe turret drives.
Principle of Operation: The RA Series operates by transmitting the rotation of a servomotor through an input gear to spur gears, reducing speed according to the gear ratio. Crankshafts connected to the spur gears rotate, causing RV gears to revolve eccentrically, reducing rotation speed proportionally to the number of pins in the system.
Warranty: Nabtesco offers a warranty covering defects due to design or manufacturing for one year or 2,000 operational hours, whichever comes first. The warranty is limited to repair or replacement and excludes defects caused by misuse, exposure to contaminants, use of non-recommended parts, or environmental factors not specified in the product's specifications.
Specifications and Model Codes: Detailed specifications for the RA Series reduction gears are provided, including model codes such as RA-20EA, RA-40EA, RA-80EA, and RA-160EA. Each model is associated with specific speed ratios, rated torque, output speed, and allowable acceleration/deceleration torque.
Performance and Limitations: Rated torque values ensure the rated service life at the rated output speed but do not represent the maximum load capacity. The allowable output speed may be limited by heat, and the surface temperature should not exceed 60°C during operation. Low temperatures can increase no-load running torque.
Technical Considerations: Optimal performance requires checking the allowable moment diagram and considering moment and torsional rigidity. Proper lubrication is crucial, especially when the rotation angle is small (10 degrees or less), as it affects the gear's service life.
Installation and Dimensions: Detailed dimensions for components such as input gears and motor flanges are provided, with specifications for both straight and tapered shafts. Specifications are subject to change without notice.
Operating Environment and Safety: The document emphasizes maintaining the reduction gear within specified temperature limits to prevent damage. It also mentions export regulations and compliance with safety measures, especially for military applications or weapon manufacturing.
Maintenance and Replacement: The standard replacement time for lubricant is 20,000 hours, adjustable based on operating conditions, particularly if the surface temperature exceeds 40°C. Regular checks on lubricant degradation are recommended.
Specifications and Operating Environment: Necessary conditions for using a reduction gear include operating within specified temperature (-10°C to 40°C), humidity (less than 85% without condensation), and altitude (below 1000 m). Installation in dusty, outdoor, or hazardous environments is discouraged.
Safety and Maintenance: Users are cautioned about potential misuse risks leading to accidents. Safety measures, such as independent safeguards, are recommended. Monitoring the reduction gear temperature to prevent it from exceeding 60°C is advised.
Technical Definitions: Key terms such as 'rated service life', 'allowable acceleration/deceleration torque', 'momentary maximum allowable torque', and 'allowable output speed' are defined to aid understanding of operational limits and performance metrics.
Product Selection and Calculation: A detailed flowchart and step-by-step guide for selecting a reduction gear are provided. This includes setting operation conditions, verifying the operating environment, and calculating various torques and speeds.
Calculation Examples: Examples illustrate calculating inertia moments, constant torque, and load torque under different configurations, helping determine the appropriate reduction gear model based on operational requirements.
Reduction Gear Selection Process: The process involves verifying various parameters such as rated torque, maximum torque for startup and stop, output speed, shock torque at emergency stop, thrust load, moment load, service life, and motor torque limitations. The RA-20EA model is selected as it meets all specified conditions.
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Catalog excerpts

RA-1

Precision Reduction Gear RV High Precision Gearhead

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RA-2

Contributing to society with our ‘Moving it. Stopping it.’ technologies Nabtesco's technologies supporting society Nabtesco manufactures products which are used in everyday life. Our high-accuracy components are essential for moving objects; they may be rarely visible, but are the foundation of everyday objects that you see moving and wonder how. Nabtesco’s technologies are found throughout objects that move and stop people’ s lives. Do or s Ro bo ts Precision reduction gears precisely move and stop industrial robots. Co ns tru cti on ma ch ine ry Running motors and control valves start and stop...

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RA-3

CONTENTSWho is Nabtesco? The key words for Nabtesco are ‘motion control'. We use our strengths in the fields of component and systems technologies to develop highly creative products. Through the Nabtesco Group as a whole, we can also utilize our advantage of expertise to maximum effect in order to further enhance these strengths. In the air, on land and at sea, we have a leading share in various fields of both international and domestic markets. Nabtesco will continue to evolve by utilizing its strengths in many fields and by exploring the possibilities of the future. April 2002 Initiation of...

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RA-4

The includes gearheads for high precision control of ATC magazines, ATC arms, APC, and turret drives of lathe machining centers. Series

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RA-5

RA Series characteristics and structure High reliability High rigidity High precision High torque Heavy load support The double-ended support design and unique pin gear mechanism provide the following advantages: (1) Capable of high shock load 5 times the rated torque (2) High torsional rigidity (3) Small backlash [1 arc.min] (4) High torque density (capable of high torque with downsized gear) A set of internal main bearings (large angular ball bearings) enables complete support of heavy external loads. 1. Compact design with a reduced number of Two benefits parts Warranty due to the 2. Reduced...

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RA-6

Examples of uses for the RA Series For machining center ATC magazine drive Cam drive for ATC arms Rotary table Contact us for NT Series rotary tables.

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RA-7

For NC lathe or combined lathe ATC magazine drive Lathe turret drive RA-EA Series RA-EC Series

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RA-8

Principle of operation 1. Rotation of the servomotor is transmitted through the Fig. 1. First reduction section input gear to the spur gears, and the speed is reduced according to the gear ratio between the input gear and the spur gears. 2. Since the crankshafts are directly connected to the spur gears, they have the same rotational speed as the spur gears. Spur gear 3. Two RV gears are mounted around the needle bearings on the eccentric section of the crankshaft. (In order to balance the equal amount of force, two RV gears are mounted.) 4. When the crankshafts rotate, the two RV gears mounted...

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RA-9

Model code RA-EA Series (Case rotating type) RA-EC Series (Shaft rotating type)

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RA-10

Note: 1. The rating table shows the specification values of each individual reduction gear. 2. The allowable output speed may be limited by heat depending on the operating rate. Make sure that the surface temperature of the reduction gear does not exceed 60°C during use. 3. For the inertia moment of the reduction gears, refer to the Product Summary Sheet. 4. When the reduction gear is used at low temperatures, there will be a larger no-load running torque. Note this characteristic when selecting a motor. (Refer to “Low temperature characteristics” on page 32) 5. The allowable moment will differ...

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RA-12

Specifications and dimensions are subject to change without notice. External dimensions Reduction gear main unit

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RA-13

M 1H Specifications and dimensions are subject to change without notice.

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RA-14

Specifications and dimensions are subject to change without notice.

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RA-16

Input gear External dimensionsStraight shaft (with key) Model

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RA-17

The asterisk (*) at the end of the order item number will be replaced with our revision number. It is subject to change without notice. The drawing above shows a representative model. The actual model may differ from the drawing. 15

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RA-19

External dimensions Motor flange Tapped hole for hanging bolt M8×14 (Flange mounting hole) 4 - ØH ØJ counterbore Motor flange code Order item number Flange outer dimensions (mm) ØA C D ØE (Tapped hole for motor mounting) 4 - Nominal P × Depth Q The asterisk (*) at the end of the order item number will be replaced with our revision number. It is subject to change without notice. The drawing above shows a representative model. The actual model may differ from

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RA-20

(Tapped hole for motor mounting) 4 - Nominal P × Depth Q Tapped hole for hanging bolt M8×14 Square type (Flange mounting hole) 4 - ØH ØJ counterbore Motor flange code Order item number Flange outer dimensions (mm) ØA C D ØE □B The asterisk (*) at the end of the order item number will be replaced with our revision number. It is subject to change without notice. The drawing above shows a representative model. The actual model may differ from the d

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RA-21

Technical Information

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RA-22

Considering the use of the RA Series This product features high precision and high rigidity, however, it is necessary to strictly comply with various restrictions and make appropriate to maximize the product’s features. Please read this technical document thoroughly and select and adopt an appropriate model based on the actual operating environment, method, and conditions at your facility. Export • When this product is exported from Japan, it may be subject to the export regulations provided in the “Foreign Exchange Order and Export Trade Control Order”. Be sure to take sufficient precautions...

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RA-23

Glossary Rated service life Torsional rigidity, lost motion, backlash The lifetime resulting from the operation with the rated torque and the rated output speed is referred to as the “rated service life”. When a torque is applied to the output shaft while the input shaft is fixed, torsion is generated according to the torque value. The torsion can be shown in the hysteresis curves. The value of b/a is referred to as “torsional rigidity”. The torsion angle at the mid point of the hysteresis curve width within ±3% of the rated torque is referred to as “lost motion”. The torsion angle when the torque...

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*Prices are pre-tax. They exclude delivery charges and customs duties and do not include additional charges for installation or activation options. Prices are indicative only and may vary by country, with changes to the cost of raw materials and exchange rates.