These machines act as follows. The movable trolley being pushed against the two rollers of the fixed frame, and the stop-pallet being raised, the prism of clay advances over the rollers, which turn and thus facilitate its motion. Having reached the pallet, it draws on by its motion the trolley, which begins to move along on its wheels; it is then that the wires are brought into use.
Fig. 140. Small Cutting table (Joly).
In the Joly machine (Fig. 101) the Mire-carrier swings on one of its sides 5, 5. The stop-pallet is fixed to an axis fitted with two counterpoises which keep it raised. In order to prevent the prism of clay when it strikes it from turning it over, one of the counterpoises is held with one hand, and with the other the wire-carrier is brought forward. The prism is cut; the pallet is released and falls (Fig. 101), the bricks are removed, the pallet is raised, and the trolley is pushed back again. The same movements are repeated, the wire-carrier being successively pushed backwards and forwards. In those cutting machines where the wire frame is fixed to the trolley (Fig, 141) the motion of the former is connected with that of the pallet, which, during the operation of cutting, is held by a piece fixed to the arms of the wire frame, and released as soon as the cutting is done.
Fig. 141. Trolley Cutting-table, cutting at an Angle (Jager).
The Groke cutter (Fig. 142) has two trolleys; the wire frame has a spring and returns automatically to its first position.
We call the preceding cutters angular because the wires attack the prism at a certain angle: others are made in which this attack takes place perpendicularly to one face of the prism; such are -
The wire frame, which is placed parallel to the rollers, is guided in its motion by two rods fixed to each side of the trolley. An arrangement of levers allows of its being brought down on to the prism of clay. In another system (see Fig. 120) the wire frame is fixed to the framework of the machine and not to the trolley.
Fig. 142. Trolley Cutting-table, cutting at an Angle (Groke).
The Borner (Fig. 144) cutting machine is arranged for making special corner cuts for arch bricks; it also cuts perpendicularly. It can be regulated to all dimensions, as the wires run between guides which can be moved at will.
In the preceding machines the wires are movable and the prism of clay is fixed; in the following ones the arrangement is reversed. The movable table is preceded by rollers, which facilitate the gliding motion of the clay. When the latter has attained a sufficient length (8 to 10 bricks) it is cut by a single wire, then the piece is pushed back from the wires against a square board. By means of the lever seen on the left in Fig. 146, and which is moved forward, the block meets the stretched wires and is divided into regular pieces, while the bricks so formed are placed on a movable tray, which has only to be taken up and placed on the barrow without the bricks being touched (Figs. 118, 126). Fig. 145 shows the arrangement of the rack-work and toothed segment, which give the backward and forward motion to the table; at the left is seen the square stop which checks the end of the prism. In these machines there is always a certain waste, owing to the difficulty of so cutting the prism that it may contain an exact number of bricks. The excess of clay beyond the last wire is useless, and must be thrown back into the machine.
Fig. 145. Cutting-table with Side Discharge (Whitehead).
Fig. 146. Culting-table with Side Discharge (Johnson).