Safety lock for rotating machinery

An apparatus for preventing the opening for one or more access doors to rotating machinery which is confined in some form of enclosure. A shaft from the machinery extends through the enclosure and has a disc attached to it. The disc has one or more radial holes drilled in the periphery to permit the entry of a release rod, but only when the machinery is stopped. The release rod is attached to a pivoted rod which is moved into and out of locking engagement with the doors when the release rod can enter the periphery hole. The pivotal rod contains two locks each for one or more doors. One lock prevents the door from being rotated toward the rod and the second lock prevents the door from being rotated away from the rod unless the pivotal rod is pivoted to release the locks.

BRIEF DESCRIPTION OF THE PRIOR ART 
Previous rotating equipment relied upon warning signs to prevent persons 
from opening access doors when the equipment was rotating. Unfortunately, 
many injuries resulted when such warning signs went unheeded. The prior 
art fails to show a safety lock actually tied directly into the rotating 
shaft thus preventing opening of the access doors until all rotation of 
the internal equipment had stopped. 
BRIEF DESCRIPTION OF THE INVENTION 
This invention describes apparatus for preventing the opening of access 
doors to an enclosure containing rotating machinery until all rotation of 
the machinery has stopped. 
The above is accomplished by attaching a disc to a shaft coupled to the 
internal rotating equipment. The disc has one or more radially drilled 
holes in its periphery. The safety lock is mounted on the side of the 
enclosure and extends to each (if there are two) door. The lock includes a 
horizontally pivoted rod which has an unlocking lever adjacent each door. 
The rod has a lever arm affixed to it over the disc. A release rod is 
attached to the leverarm and positioned so that it can enter one of the 
radial holes when the lever arm is rotated. If the machinery is rotating, 
the disc is rotating thereby making it impossible to jam the release rod 
in to one of the radial holes of the disc, preventing the rod from being 
pivoted by the lever arm. Two locks are attached between the lever arm and 
the door. The first lock prevents the door from being pivoted toward the 
lever arm when the arm is in the locked position; and the second lock 
prevents the door from rotating away from the lever when the lever is in a 
locked position.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1 and FIG. 2, an enclosure has side walls 10, a door 11, 
attached by two pairs of releasable hinges 12 and 13. Hinges 12 or 13 
comprise a rod 14, having a plurality of upper hinge portions 15, attached 
thereto. Each upper hinge portion has a hinge pin 16 illustrated by dotted 
lines, affixed in it. A lower hinge portion 17 is attached to side walls 
10 and has an axial opening to receive pin 16. A plurality of hinges (now 
shown) are positioned along rod 14 as needed to support door 11. Referring 
to FIG. 2, a similar hinge 12' is attached along the side in a similar 
fashion. 
A motor 18, is mounted to a frame portion 19, by any usual means such as 
bolts 20. A shaft 21, extends from motor 18, and has attached thereto a 
disc 22, which has a plurality of radial holes 23, drilled into it around 
its perimeter. A rod 25, is pivotally attached through a sleeve 26, to 
side wall 10, using plates 27, for example, which may be welded or bolted 
to side wall 10. At the ends of rod 25, is attached an unlocking or 
releasing lever 28. At the center of rod 25, and positioned over disc 22, 
is a bracket 29, formed from two plates 30 and 31, which are welded or 
attached at one end to rod 25. The other end has a rod 32, which functions 
as a pivot for a release rod 33. Rod 33 is slidably attached at two 
bearings 34 and 35, so that it is positioned directly over one of the 
holes 23. A spring 36, biases rod 33 away from hole 23 until downward 
pressure is applied to lever 28, in the direction of arrow 37. 
The locking mechanism for the door comprises two separate locks. The door 
11, has attached thereto a bracket 40 at one end 41, with a right angle 
bend 42, at its other end. When door 11, is closed and hinge 12 in place, 
a portion 43, of bend 42 engages lever 28. A second lock consists of a pin 
44, attached to a right angle portion 42, of bracket 40, and a bracket 45, 
which is attached to lever 28. Bracket 45 has a hole in it to receive pin 
44. 
OPERATION 
The safety locking apparatus operates in the following manner. Motor 18 
must be shut off and come to a complete standstill before release rod 33 
can enter hole 23. If the equipment is rotating and lever 28 is pulled 
downward, rod 25 will rotate causing bracket 29 to move rod 33 downward. 
The end of rod 33 will try to enter hole 23, but the machinery, since it 
is rotating, will not let the rod enter the holes 23. Lever 28 cannot be 
moved downward enough to release either of the locks. If the hinge 12' on 
the far side is removed and the door 11 swung toward the rod 25 and handle 
28, portion 43 will strike handle 28 preventing the door from opening. If 
hinge 12 is removed and the door is forced away from handle 28, pin 44 
will still be preventing any movement of the door 11. However, if the 
motor is stopped, shaft 21 is stopped and disc 22 is likewise stopped. 
Under these conditions, disc 22 can be slowly rotated until release arm 33 
drops into hole 23 when pressure is applied to handle 28. Pressure on 
handle 28 will cause rotation of rod 25, moving bracket 29 downward. This 
downward movement will cause release rod 33 to enter hole 23, overcoming 
the bias of spring 36. The continued downward movement of arm 28 after rod 
33 enters hole 23 moves handle 28 away from in front of portion 43. It 
also moves the handle downwardly along with bracket 45 releasing the 
portion 43 to move in either direction. 
A similar locking apparatus can be provided for one door or doors at each 
end as illustrated. 
It is obvious that the shaft can extend from the motor as illustrated or 
the shaft can be an internal shaft. It is also obvious, that the disc can 
be inside or outside the enclosure. If it is inside the enclosure, the rod 
33 must enter the housing through a hole in the enclosure, or other lever 
arms can be incorporated to accomplish the same result. 
Changes can be made in the invention as disclosed in the specifications or 
claims and still be within the spirit and scope of the invention as 
defined in the apended claim.