15,698. Leblanc, A. D. July 14. Braces and other hand-drills.-Relates to ratchet mechanisms particularly suitable for screwdrivers, but also adapted for wood and metal working tools such as bits, drills, and boring-tools generally. In one form, shown in Figs. 2 and 7 as applied to a screwdriver, ratchet-wheels 39, 42 are pinned to the shank 38 of the blade 37, and can be engaged by one or both of two ratchet-wheels 51, 52 loose on the shank and pressed apart by a spring 53. The wheels 51, 52 have pins 59 passing through longitudinal slots 58 in a sleeve 54 pinned to the handle 36 so that these wheels always rotate with the handle. The pins 59 project into slots 64, 65, 66 in a cam sleeve 60 actuated by an external sleeve 61 secured to it.The cam sleeve may be left in the central position shown in Fig. 2, when both pairs of ratchet-wheels are in engagement and the screwdriver acts as a "solid" one, or the sleeve may be turned to draw one of the wheels out of engagement, the remaining wheel imparting a ratchet drive to the blade in the corresponding direction. The pin 56 securing the sleeve 54 to the handle engages a slot 67 in the cam sleeve, allowing the cam and external sleeves to be withdrawn when in the central position. Fig. 18 shows a form of spiral screwdriver, the spindle 71 having right and left hand helices, and carrying the blade or other tool. The upper and lower ratchet-wheels 74, 75 are not pinned to the spindle as in the previous form, but have internal lugs engaging the helices, each wheel engaging one helix. The wheels are held against end movement in the handle sleeve 84. Intermediate wheels 88, 89, a cam sleeve 97, and an external sleeve 103 are arranged as in the previous form, so that both pairs of wheels may be left in gear to prevent relative movement of the spindle and handle, or only one pair may remain in gear to cause the spindle to rotate in one direction or the other only when the handle is pressed down over the spindle. When the handle is in its lowest position, the tool acts as a reversible ratchet screwdriver by turning the handle. In a modification of this form, one pair of ratchet-wheels is omitted, and both helices run in the same direction, the tool becoming a single-acting spiral screwdriver. The upper end of the spindle has ratchet teeth which can engage similar teeth in the handle when the handle covers the spindle, thus causing the tool to act as a solid screwdriver, but, by turning the cam sleeve which has only one inclined slot, the ratchetwheels are separated, the ratchet teeth then enabling the tool to be used for unscrewing. In a further modification, a development of the preceding form, the arrangement for spiral screwdriving in one direction is as before, but to allow the tool to be used as a ratchet screwdriver in either direction, the teeth on the upper end of the spindle engage a ratchet-wheel held against rotation by lugs engaging longitudinal slots in the handle sleeve, and passing through into a second cam sleeve. The spindle only engages the upper ratchet-wheel when the handle is in its lowest position, the tool then having a ratchet unscrewing action if the lower pair of wheels are disengaged. By engaging the lower pair, and disengaging the upper wheel from the spindle, the tool has a ratchet screwing action.