1. Field of the Invention
The present invention relates to air pressure regulation of pneumatic motors in handheld dehiders and powered skinning knives used to remove the hide of a carcass in a meat processing facility, particularly dehiders that use a pair of cutting disks driven in opposed cutting oscillations.
2. Description of Related Art
Handheld dehiders are used in meat processing facilities to remove the hide from an animal carcass. The most common type of dehider includes a pair of adjacent cutting disks or blades that are driven in opposed cutting oscillations by a corresponding pair of pushrods. The basic designs are shown in U.S. Pat. Nos. 5,122,092, 7,722,448 and 7,963,829 assigned to Jarvis Products Corporation, the assignee of the present invention. Other dehider designs are shown and described in U.S. Pat. Nos. 4,368,560, 3,435,522 and 2,751,680.
In the dehider design described in the patents above, each cutting blade includes teeth around its perimeter. The adjacent disk blades are driven in opposed cutting oscillations by a pair of pushrods connected to an eccentric drive mechanism operated by a pneumatic motor mounted in the handle of the tool. The motor rotates a pinion gear, which turns a main drive gear oriented at ninety degrees to the axis of the motor. The main drive gear turns the eccentric shaft to oscillate the pushrods. During each oscillation, the teeth on one disk blade move past the teeth on the adjacent and oppositely moving disk blade. This produces between adjacent and oppositely moving teeth a shearing and cutting action that quickly removes the hide from the carcass. The disclosure of the dehiders and powered skinning knives of the aforementioned patents, and their methods of operation, are hereby incorporated by reference.
To prevent the dehider from tending to slow down under a heavy cutting load, and permit it to operate at a nearly constant speed when operating under a load and when operating without a load, the '448 and '829 patents provided a speed governor for the pneumatic motor. The speed governor is disposed in the housing between the air inlet for the pressurized air and the motor, and automatically controls the flow of pressurized air to the pneumatic motor to maintain a desired rotational speed for the motor.