Hold down clamp
View Patent ↗A base drum rim clamp device comprising in combination, a base, a wedging device to exert clamping force that device carried by the base, means to displace said device to move a surface or surfaces of the device relatively toward one side of a base drum rim, and a clamp part to which clamping force is transmitted at the opposite side of the drum rim.
1. A base drum rim clamp device comprising in combination.
a) a base,
b) a wedging device to exert clamping force, that device carried by the base,
c) means to displace said device to move a surface or surfaces of the device relatively toward one side of a base drum rim, and
d) a clamp part to which clamping force is transmitted at the opposite side of the drum rim,
e) said device comprising two horizontally separated and angled wedges carried for adjustable relative movement in the same horizontal plane toward one another, or away from one another,
f) the base having structure that extends in the horizontal direction of wedge separation and guides such wedge relative movement,
g) whereby only three-point clamping support for the drum rim is provided.
2. The combination of claim 1 including the drum rim which is arcuate, and is supported on the wedges, at spaced locations.
3. The combination of claim 1 wherein both wedges are slidably carried for simultaneous relative movement toward one another, or away from one another.
4. The combination of claim 1 wherein said structure defines a channel, along which both wedges are movable.
5. The combination of claim 2 wherein the wedges have substantially flat surfaces that extend in tangential contact relative to the arcuate rim.
6. The combination of claim 1 wherein said means to displace the device includes a displacer having screw thread operative connection to the device.
7. The combination of claim 1 wherein said means to displace the device includes an adjustably rotatable displacer having screw thread operative connection to the wedges.
8. The combination of claim 7 wherein the displacer has differential screw thread operative connection to the wedges, whereby, as the displacer is rotated in one rotary direction the wedges are relatively displaced toward one another, and as the displacer is rotated in the opposite rotary direction, the wedges are relatively displaced away from one another.
9. The combination of claim 8 wherein the wedges have aligned bores which are threaded to receive differential threading on the displacer, whereby both wedges are moved, to clamp the drum rim in response to simple rotation of the displacer in one direction, and with mechanical advantage.
10. The combination of claim 9 wherein the threaded bores and said displacer threading define worm gearing, which prevents unclamping of the rim during drum beating.
11. The combination of claim 1 including a pedal unit having a base plate supporting said base, a pedal pivotally carried by the base plate, a drum beater pivotally carried by the base plate, and a drive connected between the pedal and the drum beater.