Page 45 of catalogue Miniature couplings of PM Bearings B.V.

• MJT

Selecting MJT Couplings
Due to its unique construction, MJT couplings exhibit features not seen in other coupling types. This coupling consists of both side hubs and an elastic sleeve pressed in the hubs. MJT couplings combine the features of a metallic spring coupling with zero backlash and a flexible coupling with an elastic rubber sleeve. Therefore, MJT couplings can be used for rotational angle transmission with zero backlash and for torque transmission. There are three different types of sleeves with different hardness. Check the following points for the proper selection of MJT couplings.

➊ Zero Backlash Transmission
In applications where rotational angle transmission and motion control at low torque are needed, MJT couplings can be used like metallic spring couplings with zero backlash. In addition, MJT couplings can absorb torsional vibration, which other zero backlash couplings cannot absorb. The permissible torque in zero backlash applications is smaller than the rated torque mentioned in the specification Tables. Please refer to the table below. Any of the three different sleeves have the same permissible torque in zero backlash applications, however, the harder the sleeve the better the response of angular transmission. You may select the best sleeve for your requirements, referring to the static torsional stiffness in the table below or the specification tables.

➋ Torque Transmission
The MJT, a compression type coupling, can transmit generally higher torque than metallic spring couplings, and this coupling can be recommended for the applications of general industrial machinery like Pumps, where a backlash is acceptable. The rated and maximum torque of blue, white and red sleeves are respectively low, medium and high, while the permissible misalignment of blue, white and red sleeves are respectively large, medium and small. You may select the most suitable sleeve for your application. For torque transmission applications, we recommend an MJT with keyway (MJT-✽✽K) or an MJT with clamp hub and keyway (MJT-✽✽CK) for safe and sure shaft attachment.

Catalog Number

Zero Backlash Hardness✽ Permissible Torque of Sleeve (N m)

Rated✽✽ Torque (N m)

Max.✽✽ Torque (N m)

Static Torsional Stiffness (N m/rad)

Errors of Eccentricity (mm)

Errors of Angularity (° )

Errors of Shaft End-Play (mm)

BL MJT-14 WH RD BL MJT-20 WH RD BL MJT-30 WH RD BL MJT-40 WH RD BL MJT-55 WH RD BL MJT-65 WH RD

80 92 98 80 92 98 80 92 98 80 92 98 80 92 98 80 92 98 — — 1.2 0.5 0.2 0.1

000.7 001.2 002.0 001.8 003.0 005.0 004.0 007.5 012.5 004.9 010.0 017.0 017.0 035.0 060.0 046.0 095.0 160.0

001.4 002.4 004.0 003.6 006.0 010.0 008.0 015.0 025.0 009.8 020.0 034.0 034.0 070.0 120.0 092.0 190.0 320.0

0008 0014 0022 0016 0029 0055 0046 0073 0130 0380 0570 1200 1400 1600 2600 2800 3000 4900

0.15 0.10 0.10 0.20 0.15 0.10 0.20 0.15 0.10 0.15 0.10 0.10 0.20 0.15 0.10 0.20 0.15 0.10 1.0 1.0 1.0 1.0 1.0 1.0

+0.6 +0.0

+0.8 +0.0

+1.0 +0.0

+1.2 +0.0

+1.4 +0.0

+1.5 +0.0

✽✽ Durometer hardness (Shore A). ✽✽ Operational temperature of MJT is –20°C~60°C. The rated and max. torque capacities are decreased in case of use in high ambient temperatures. If the ambient temperature exceeds 30°C, adjust the torque capacity, referring to page 5.

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