FIG. 43.—LOOM WITH SMALLEY’S MOTION. To face pp. 98 and 99.
The tappet is fixed on the upper frame-work of the loom and short treadles arranged above it. To these the healds are attached and lifted by the plates, being drawn down afterwards by springs and the healds. In a recently-improved form the treadles raise the jacks to which the healds are attached, giving a straight lift. These tappets are seldom used for more than 8 healds and 12 picks to the round. Above this extent in tappet work, a Woodcroft sectional tappet is used, arranged at the loom side. In these tappets the projections (called risers and fallers) are removable, the tappet being adaptable to different patterns up to 14 staves and 20 picks. In the Yorkshire loom, [Fig. 23], the tappets are placed at the loom side, and are connected with the top of the healds by rods.
Tappets possess the advantage over other shedding motions of larger capacity, such as the dobby: (a) in lower first cost; (b) steadier and stronger lift without risk of hooks slipping; (c) in having a split shed—i.e., a shed which has one portion pulled down while the other is drawn up, saving time. Dobbies and jacquards generally have a sunk shed, and if by those machines a shed 2 inches deep is required, the lifting knives have to be raised the whole distance, from the bottom to the top.
FIG. 44.
FIG. 45.