US3495424A

US3495424A - Master lock

Info

Publication number: US3495424A
Application number: US584834A
Authority: US
Inventors: John F Kleinschmidt
Original assignee: JOHN F KLEINSCHMIDT
Current assignee: JOHN F KLEINSCHMIDT
Priority date: 1966-10-06
Filing date: 1966-10-06
Publication date: 1970-02-17
Anticipated expiration: 1987-02-17

Description

Feb. 17, 1970 MASTER 1.00K` Filed oct. e, 19661:*

Illu

FIG. 2.

INVENTOR. JOHN F. KLEINSCHMIDT wwf@ FIG. 3.

ATTORNEYS United States Patent O U.s. c1. 'lo-151 2 Claims ABSTRACT F THE DISCLOSURE In a pin tumbler master lock, a cylinder comprising a cylinder shell having a cylindrical bore, a rotatable plug mounted in the bore and having a keyway formed therein, a series of pinholes formed in the bore and shell, a combination of pins positioned in the pinholes and being adapted to accept the number of individual keys to rotate the plug, a cam mounted on the plug and rotatable thereby for actuating a latch bolt, and apparatus for preventing pins from dropping out of the cylinder by restricting rotation of the plug to less than 180. A spring automatically returns the plug to normal locked position if a key should be withdrawn from the keyway at other than normal locked position.

This invention relates to improvements in a master lock, and more particularly concerns a master lock having means for preventing pins from dropping out of the cylinder.

A master lock for the main door of a large apartment building, say four or live hundred apartments, must open upon insertion of every apartmet key. In other words, each apartment key must fit its apartment door lock and also lit the lock at the main door of the apartment building.

If the main door lock malfunctions, then many tenants are unable to enter the apartment building because they are prevented from opening the front door. This brings complaints from the tenants, and is a fairly common occurrence.

Master locks are made to accommodate a number of keys by dividing the pins into a number of master pins or wafers so that each key positions the master pins at the shear line of the cylinder plug so that the .plug is free to rotate. One of the causes for a malfunctioning of a master lock is that the master pins drop out of their position in the pinholes and jam the lock mechanism or drop out of the cylinder completely. With some of the master pins missing, some keys will not position one or more pins at the shear line and as a result the plug is prevented from rotating.

Accordingly, it is an object of this invention to provide a master lock which overcomes the problems of the prior art by preventing master pins from dropping out of position and from dropping out of the cylinder.

It is another object to provide a master lock which is prevented from rotating to a position 180 away from its normal locked position.

It is another object to provide a master lock which automatically returns to normal locked position if a key should be withdrawn from the plug at another position.

Other objects and advantages of this invention, including its simplicity and economy, as Well as the ease with which it may be adapted to existing equipment, will further become apparent hereinafter and in the drawings, in which:

FIG. 1 is a view in side elevation of a master lock constructed in accordance with this invention with the bolt stop plate removed in order to show the structure of the invention more clearly;

FIG. 2 is a view in section as indicated by the lines and arrows 2 2 which appear in FIG. 1;

FIG. 3 is a partial view similar to that of FIG. 2 but showing the lock in its open position with the latch bolt retracted; and

FIG. 4 is a view in section of the cylinder.

Although specific terms are used in the following description for clarity, these terms are intended to refer only to the structure shown in the drawings and are not intended to dene or limit'the scope of the invention.

Turning now to the specific embodiment of the invention selected for illustration in the drawings, there is shown a pin tumbler master lock which includes a cylinder 11 having a cylinder shell 13 with a cylindrical bore 15, and a cylinder face 17. Cylinder 11 is provided with threads 19 that are threaded into a hole in lock case 21. A cylinder set screw 23 is mounted in case 21 and extends into a groove 25 formed in the outer surface of cylinder shell 13 for setting shell 13 against further rotation when it has been rotated into its proper position.

A rotatable plug 27 is mounted in bore 15 and has a keyway 29 formed therein.

A series of pinholes 31 are formed in shell 13, and another series of pinholes 33 are formed in plug 27.

Pinholes

31 and 33 register with each other when the plug is in its normal locked position. A number of pins 35 are positioned in

pinholes

31 and 33 and are urged downwardly by pin springs 37 which are positioned in the head portion of pinholes 31.

When a cylinder is locked, pins 35 extend across a shear line 36 formed lbetween plug 27 and shell 13 and prevent rotation of the plug. When a proper key is placed in keyway 29, such as key 38, gulleys 39 of the key contact and lift the pins 35 so that ends of pins 35 coincide with the shear line, thus permitting rotation of plug 27 in shell 13.

Since a number of pins 35 are positioned in each pinhole, the combination of pins 35 is adapted to accept a number of individual keys to rotate plug 27.

yCase 21 includes a miounting face 41, an armor faceplate 43, and a bolt stop plate 45. A retaining screw reinforcing plate 47 is mounted on the inner side of mounting face 41 and is threaded to receive cylinder set screw 23, and a cam mechanism 49 is mounted on inner end 51 of key plug 27.

One way in which master locks of the prior art have been caused to malfunction is to rotate keyway 29 to a position away from the normal locked position shown in FIG. 2 so that keyway bottom 53 is positioned below the pins in shell pinholes 31. If the key is then withdrawn from the keyhole in that position, pins 35 fall from pinholes 31 into keyway 29 to become lodged there and prevent rotation of plug 27. It will be realized that a key with a low cut at its end can be withdrawn from the keyway at this 180 position, even though a key with a high cut at its end might not be withdrawable except at the normal locked position at which position the withdrawal of the key pushes pins 35 upwardly into upper pinholes 31.

If the pins 35 falling into bottom 53 of keyway 29 do not jam across the shear line but fall completely into the keyway, the subsequent insertion of a key pushes the fallen pins out of the cylinder. Because of the missing pins, some of the keys subsequently inserted do not position the pins so that their ends coincide with the shear line. Accordingly, those keys cannot rotate the plug 27.

Another cause of malfunctioning of conventional master locks is to withdraw a key having a low cut at the end from the key at a position somewhere between the normally locked position and the 180 position, leaving a number of pins in plug pinholes 33. The subsequent insertion of another key cannot push the pins into the shell pinholes 31 because the plug pinholes are not in register with them. Accordingly, keys with high cuts cannot be inserted into the keyway 29 until the plug 27 is rotated to the normal locked position.

Keys can be withdrawn from the keyway 29 at other than normal locked position because of wear of the key and parts of the lock mechanism. The open ends of bore pinholes 33 adjacent the outer surface of plug 27 are made larger by wear so that the tumbler pins 35 do not have to be at the shear line 36 in order to open the lock, thereby permitting a loose t whereby the tumbler pins 35 in plug 27, at said other position than locked, have freedom of movement allowing the key to be withdrawn.

To avoid these diiiiculties, my invention provides means for preventing pins 35 from dropping out of cylinder 11, and includes means for preventing rotation of the plug 180 from normal locked position, and means for automatically returning the plug 27 to normal locked position if a key should be withdrawn from keyway 29 at other than normal locked position.

Referring to the drawings, cam mechanism 49 includes an operating cam 55 which extends downwardly from key plug 27 and extends outwardly from the periphery of the cylinder. Cam 55 contacts a retracting arm 57 mounted on a latch bolt 59 that is slidable in case 21 and is urged outwardly to its locked position as shown in FIG. 2 by a spring 61 mounted on bolt stop plate 45.

In operation, rotation of plug 27 by a key causes rotation of cam 55 which moves arm 57 to retract the latch bolt 59 from the extended or locked position shown in FIG. 2 to the retracted or open position shown in FIG. 3. Bolt stop plate 45 limits the retracting movement of the bolt 59 so that plug 27 cannot rotate 180 clockwise, viewed from the front of the lock.

If a key 37 should be withdrawn from keyway 29 at any position other than the normal locked zero-degree position, plug 27 is automatically returned to that position by spring 61 which pushes latch bolt 59 to its extended position so that retracting arm 57, which bears against operating cam 55, rotates cam 55 and plug 27 to normal locked position.

A boss v63 extends from each side of bolt 59 and rides in slots 65 formed in case 21. The extending motion of bolt I59 is limited by the end of slots 65.

A guard 67 is provided which when retracted prevents latch bolt 59 from being retracted from its locked position by any force which might be exerted against the head of the latch bolt such as by a card slipped into the crack between the door and jamb.

Cam mechanism 49 also includes a hold-open cam 6 that actuates a rotatable hold-open member 71 having a catch 73 adapted to contact the arm 57 and hold it in retracted position when it is desired that the lock remain open, as during the daytime. Hold-open member 71 is rotated in a counterclockwise direction, viewed from the front of the lock, by turning hold-open cam 69 counterclockwise with the key after pushing latch bolt 59 by 4 hand to its retracted position. The hold-open member 71 is returned to normal position by rotating operating cam S5 in the clockwise direction, again viewed from the front of the lock, so that cam 55 pushes arm 57 against member 71 to rotate it. A stop post 75 limits the counterclockwise rotation of hold-open member 71, and a stop post 76 limits its clockwise rotation. When member 71 is in contact with post 76, it limits the counterclockwise rotation of the plug 27 by providing a stop for cam 69.

The master lock of the present invention prevents pins from dropping from the cylinder shell into the bottom of the keyway because it prevents rotation of the plug to the position away from the normal locked position.

If a key is removed from the keyway when the keyway is at a position other than the normal locked position, the pins in pinholes 33 prevent insertion of subsequent keys having high cuts. The present invention prevents such malfunction by automatically returning the plug to the normal locked zero-degree position, and does so by using existing lock elements since it utilizes the latch bolt spring, rather than using separate or additional elements.

It is to be noted that the method of inserting a cylinder into a lock in the present invention is different from the insertion of cylinders having conventional cams. In the present invention, the plug and cam are rotated 180 by the key so that the cam lies within the periphery of shell 13. Then cylinder 13 is screwed into lock case 21 to its proper position. After this, the plug and cam are rotated 180 into their proper position, wherein the cam extends beyond the circumference of the cylinder shell as shown in FIG. 2.

It is important to note that cam mechanism 49 is reversible so that it works on locks set up for left hand and right hand operation of the door.

It is to be understood that the form of the invention herewith shown and described is to be taken as a presently preferred embodiment. Various changes may be made in the shape, size and arrangement of parts. For example, equivalent elements may be substituted for those illustrated and described herein, parts may be reversed, and certain features of the invention may be utilized independently of the use of other features, all without departing from the spirit or scope of the invention.

What is claimed is:

1. In a pin tumbler master lock, a cylinder with a shell and cylindrical bore, a rotatable plug mounted in the bore and having a keyway formed therein with a bottom slot, a series of pinholes formed in the lbore and connected to the keyway, a series of pinholes formed in the shell and connected with the bore pinholes at normal locked position, a combination of pins positioned in the pinholes for accepting a number of individual keys to rotate the plug, cam means mounted on the plug and rotatable therewith, said cam means including a bolt-retracting cam for retracting a latch bolt, said bolt-retracting cam being normally in contact with the latch bolt, said cam means including a hold-open cam located on the 0pposite side of the keyway from the bolt-retracting cam for moving a hold-open member into engagement with the latch bolt to hold the latch bolt in open position, and stop means for limiting rotation of the cam means and plug to less than 180 from normal locked position to thereby prevent the pins from dropping out of the cylinder pinholes into the keyway bottom slot when a key is removed and later being lost by being pushed longitudinally through the keyway upon insertion of a key.

2. The device of claim 1, including means for automatically returning the keyway to normal locked position when a key is removed from the keyway at any other position, so that the pinholes and therefore the pins will be in normal alignment and will accept another key made for the same master series.

(References on following page) References Cited UNITED STATES PATENTS Yale et al. 70-380 X Taylor 70--380 X Taylor 70-380 X Klinzing 70-134 Taylor 70-380 X Smith 70--377 X Pickop.

Arens et al 70-408 X 6 1,693,028 ll/l928 Gage 70-379 X 3,073,143 1/1963 Eads 70-151 FOREIGN PATENTS 5 22,980 4/1918 Denmark.

RICHARD E. MOORE, Primary Examiner R. L. WOLFE, Assistant Examiner 10 U.s. C1. X.R.