Abstract: An overhead hoist transfer (OHT) apparatus and a differential overhead trolley thereof are provided. The OHT apparatus includes a rail module and a differential overhead trolley. The rail module includes a main rail and a first rail, and defines a turning path extending from the main rail to the first rail. The differential overhead trolley is movably disposed on the rail module, and includes a walking mechanism and a carrying body that is hung on the rail module by being connected to the walking mechanism. The walking mechanism includes two differential wheels and a driving unit that is connected to the two differential wheels. When the differential overhead trolley is moved along the turning path, the driving unit is configured to drive the two differential wheels to move along the first rail by different rolling velocities.

Abstract: An overhead hoist transfer (OHT) apparatus and a differential overhead trolley thereof are provided. The OHT apparatus includes a rail module and a differential overhead trolley. The rail module includes a main rail and a first rail, and defines a turning path extending from the main rail to the first rail. The differential overhead trolley is movably disposed on the rail module, and includes a walking mechanism and a carrying body that is hung on the rail module by being connected to the walking mechanism. The walking mechanism includes two differential wheels and a driving unit that is connected to the two differential wheels. When the differential overhead trolley is moved along the turning path, the driving unit is configured to drive the two differential wheels to move along the first rail by different rolling velocities.

Abstract: A CNC grinding machine includes a base having a first plane surface which can be defined by two axes perpendicular with each other, a work station driven by a first servomechanism to be capable of moving on the first plane surface and rotating about a third axis perpendicular to the first plane surface, a grinding wheel driven by a second servomechanism to be capable of moving along a first line perpendicular to the first plane surface and rotating about a fourth axis perpendicular to a second plane surface having a normal line parallel to the first plane surface, a grinding wheel dresser for dressing the grinding wheel, a measuring probe driven by a third servomechanism to be capable of moving along a second line perpendicular to the first plane surface, a CNC system controlling the servomechanisms so that a work piece can be worked and measured according to instructions stored therein and a computer connected to the CNC system and capable of governing the instructions.