Abstract: In a negative dobby for forming the warp shed in weaving looms, impacts and friction are reduced and consequently vibrations and noise-thereby improving the stability of the heald frames-by suitably shaping the rear end (14) of the hooks ( 7, 8), so as to facilitate the oscillation thereof only when they engage with the crooks (9, 10) which cooperate with the hooks.

Abstract: Mechanism to control the oscillations of connecting rods operating the heald frames in a rotary dobby, of the type wherein, for each frame and connecting rod: the rod is mounted on a drive shaft by way of an eccentric interposed between the shaft and the connecting rod small end; the eccentric can be controlled for rotation, alternatively with the connecting rod or with the shaft, by means of a radial key; mechanism is provided to shift the key to the outer position of engagement of the connecting rod small end; a spring is provided to return the key to the inner position of engagement of the shaft; and an electromagnet is provided to hold, when energized, the key in the outer position of engagement of the connecting rod small end.

Abstract: In a negative dobby for forming the warp shed in weaving looms, the stresses on some of the machine components are greatly reduced, whereby a more precise control of the heald frames is obtained, thanks to the fact that the controls transmitted to the crooks (9, 10), engaging the hooks (7, 8), by the means (12) reading the pattern of the fabric to be woven, are no longer affected by the strains deriving from the stresses imparted on said crooks (9, 10). This is obtained by operating the crooks (9, 10) by means of two-armed levers (13), controlled by the spiked roller (12)--forming the pattern reading means--and connected by spring means (17) to a square arm (18) of said crooks (9, 10), the rocking movements of said crooks (9, 10) and of said two-armed levers (13) being controlled by two distinct shafts (9A, 14).

Abstract: The invention provides improvements in the members of a loom dobby reading unit, which enable the reading unit and control unit to be structurally separated. For this purpose, the reading unit rockers act on the control unit by simple bearing and thrust contact between a tappet provided on the rockers and the horizontal needles for the lifting rods of the control unit hooks. In addition, there are provided a very rigorous guide for the reading unit rocker movements, an improved mechanism for controlling the lowering movements of the rocker thrust rods, and an improved mechanism for controlling the pressure bars, said mechanisms both using precise cam controls.

Abstract: An improved dobby uses linkages for controlling the oscillations of the fixed and mobile knives about their axes which comprise first levers fixed to the knives, second levers fixed to control shafts, and connecting rods which link said first and second levers together to form an articulated parallelogram.In this dobby, the hook operating rods are controlled by the same shafts which control the knife oscillations, by means of an articulated joint.

Abstract: Improved means are provided in a loom dobby for taking-up play in the control unit. The surfaces of the fixed and mobile blades which limit the stroke of the rocker arms in this unit are positioned perpendicular to the line joining the points of contact between the dobby hooks and knives to the mean points of contact between said blades and the rocker arms. Moreover, said surfaces are concave in the fixed blades and convex in the mobile blades. The linkage which cause the mobile knives to oscillate are in the form of false articulated parallelograms.