Case Study| Kohara Gear Industry Co.,Ltd.

The standard method for mounting gears and shafts is the key and set screw method.
However, customers have reported that this method makes it difficult to achieve precise concentricity with the shaft. Furthermore
, it is challenging to rotate the gears into position when assembling them, which imposes significant restrictions on the assembly sequence. Additionally, depending on the operating environment, the shaft mounted on the gear may experience fretting, which can hinder maintenance.
Furthermore, while methods such as shrink fitting can ensure concentricity, they make phase alignment difficult and, above all, make disassembly difficult. Although a great deal of time is spent on adjustments during assembly
, it is becoming increasingly difficult to secure personnel capable of performing these adjustments in the first place.

I was aware of mechanical-type shaft fasteners, but I wasn’t particularly impressed with them because they required a large number of bolts, and tightening the bolts would pull on the outer sleeve, causing the gear to shift axially. This meant I had to account for the amount of movement in advance and adjust the setup accordingly.
That’s when I first learned about the hydraulic-type ETP bushing and became interested in it.
The ETP bushing guarantees a concentricity of 0.006 mm—an extremely high precision—achieved by tightening a single bolt. Since there is no axial movement, as seen with mechanical shaft fasteners, assembly has become simple without the need for complex adjustments. I would highly recommend this to
users who are struggling with the assembly of high-precision custom gears.