Nabtesco RV series high-precision gearbox

There are two ways to fix the output shaft:

Bolt clamping type: Directly press the output shaft and load side flange with bolts.

Bolt+taper pin clamping type: Adding a taper positioning pin on the basis of bolt connection to transmit greater torque and withstand alternating loads. Suitable for high torque or high impact working conditions.

3.4 Selection Process

When selecting, the following steps should be followed:

Determine load conditions: including starting torque, uniform torque, braking torque, corresponding speed, and duration of action.

Calculate the average output torque and average output speed.

Calculate the expected lifespan based on the rated lifespan formula:

Lh=K × NoNm × (ToTm) 103L h=K × N m N o × (T m T o) 310, where K is the rated life base (usually 6000-10000 hours), NoN o and ToT o are the rated speed and torque, and NmN m and TmT m are the actual average speed and torque.

Verify whether the peak torque (acceleration/deceleration, emergency stop) exceeds the allowable value.

Verify whether the external bending moment and axial force are within the allowable range of the main bearing.

Select the input gear form and speed ratio based on the motor shaft diameter and speed ratio requirements.

RV-C Series: Center Thread Precision Reducer

4.1 Structural Differences and Application Scenarios

Unlike the E series, the RV-C series integrates a center gear at the input end. The central gear is a hollow structure that allows cables, air pipes, and liquid pipes to pass through the center of the reducer, thereby achieving "hollow wiring" of the robot joints. This design is crucial for situations where cables need to be avoided from being exposed or worn, such as robot wrists and base rotation axes.

The main models of the RV-C series include RV-10C, RV-27C, RV-50C, RV-100C, RV-200C, RV-320C, and RV-500C. Some models (such as RV-500C) cover extremely heavy-duty applications.

4.2 Performance parameter characteristics

The basic performance indicators of the RV-C series are similar to those of the E series, but there are the following differences:

The bending moment stiffness and allowable bending moment are generally higher than the E series of the same size, because the design of the C series focuses more on bearing larger external loads.

Accuracy requirements for central gears: Central gears are divided into large central gears and small central gears, and the tooth surface accuracy of both must reach JIS level 4 and 5. The center distance tolerance during installation is ± 0.03 mm.

Speed ratio calculation: The total speed ratio of RV-C is equal to the speed ratio of the built-in reducer multiplied by (the number of teeth on the large central gear/the number of teeth on the input gear), making the speed ratio configuration more flexible.

4.3 Installation precautions

The fixing method of the output shaft is also divided into bolt clamping type and through-hole bolt clamping type.

The clearance between the central gear and input gear should be controlled within the recommended range (such as 0.060-0.140 mm for RV-100C) to ensure smooth transmission and longevity.

Due to the presence of a central threading hole, the sealing requirements for lubricating grease are higher. O-ring or sealant (such as Loctite 5699) should be used on the mating end face to prevent grease leakage into the hollow area.

RV Universal Series: Inheritance and Compatibility

The RV universal series includes models such as RV-15, RV-30, RV-60, RV-160, RV-320, RV-450, RV-550, etc. Its structure is highly similar to the E series, with the main difference being:

Some old models (such as RV-15, RV-30) use 2 crankshafts instead of 3, so the allowed peak torque is 200% of the rated torque, while other new models are 250%.

In terms of speed ratio options, the universal series includes some intermediate speed ratios that are not available in the E series.

The external dimensions and installation interfaces are slightly different from the E series, so careful verification is required when selecting.

For new designs, it is recommended to prioritize the RV-E or RV-C series for better performance support and spare parts supply.

Lubrication and maintenance

6.1 Lubricating grease selection

Nabtesco recommends using Molybdenum RE00 grease. This is a special lubricating grease containing molybdenum disulfide, which has excellent extreme pressure resistance and low-temperature flowability. It is strictly prohibited to mix with other lubricating greases.

6.2 Oil injection volume

The oil injection amount depends on the installation direction:

Horizontal installation: Less oil, such as RV-160E requiring 448 cc.

Vertical installation: More oil is needed to prevent insufficient lubrication of the upper bearing, such as RV-160E which requires 514 cc.

When injecting oil, it is necessary to reserve about 10% of the internal space to avoid damaging the oil seal due to internal pressure increase caused by thermal expansion or agitation.

6.3 Replacement cycle

Under clean conditions with an ambient temperature below 40 ℃, the standard replacement cycle is 20000 hours. If the ambient temperature is higher or there is dust or moisture pollution, it is necessary to shorten the replacement cycle or regularly check the condition of the lubricating grease.