- The table moves in a cross direction when the crossfeed screw is rotated.
- A crank handle is provided to rotate the the crossfeed screw manually.
- When the crossfeed screw is rotated in clockwise direction, the table will move towards left.
- When the elevating screw is rotated, the table slides up and down on the face of the column.
- As the handles meant for crossfeed screw rotation and elevating screw rotation are placed side by side, it is not possible to operate both of them at the same time.
- The work mounted on the table is provided with required feed only during the end of the return stroke.
Ratchet and Pawl Mechanism (Automatic Feed Mechanism for the Table)
The table of a shaping machine travels in a cross direction when the crossfeed screw is rotated. The cross feed screw is attached to the ratchet wheel. A spring loaded ‘pawl’ is positioned to be placed between the teeth of the ratchet wheel. The pawl is housed within a frame known as rocker arm. The bull gear placed inside the column of the shaping machine drives the gear B through the gear A.
There is a diametric slot provided on the face of the gear B. A crank pin is attached to a slider placed in the slot. The bottom of the rocker arm and the crank pin are connected by a connecting rod. The rotation of the gear B makes the crank pin to rotate. This movement makes the rocker arm to rock about the centre of the ratchet wheel. The pawl makes the ratchet to rotate by a small amount in one direction only. As the cross feed screw is attached to the ratchet wheel, the rotation of the ratchet wheel will make the table to move in a cross direction.
If the direction of the table feed is to be reversed, the pawl is turned about 180° from its position. The ratchet wheel and the crossfeed screw will rotate in the opposite direction resulting in the table movement in the opposite direction.
When power feed is not necessary for the table, the pawl is disengaged from the ratchet wheel.