US1377487A - Safety device for drills - Google Patents

Description

H. V. JOHNSON. SAFETY DEVICE FOR DRILLS.

APPLICATION FILED APR.12, I920.

Patented May 10,1921.

PTENT OFFICE.

HENRY V. JGL-INSON, OF ST. PATTI], IJZINNESOTA.

SAFETY nnvrcn non prams Specification of Letters Patent.

Patented May 10, 1921.

Application filed April 12, 1920. Serial no. 373,317.

To all whom it'ma z concern:

Be it known that I, Hmvnr V. JonNsoN, a citizen of the United States residing at 7 85 Geranium St. east, St. l aul, in the county of Ramsey and State of Minnesota, have invented certain new and'useful Tmprovements in Safety Devices for Drills; and I do declare the'following to be a full, clear, and exact description of the invention such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to an improved safety device for use in connection with a large drill or other tool or machine which is slidably mounted upon a track for vertical sliding movement and one object of the invention is to provide a safety device which will be held inoperative under normal conditions, but which will be released in case the supporting chain or cable should break and thus permit the safety device to engage a rack carried by the track and thus prevent the drill from sliding downwardly of its own weight. It often happens that the supporting chain or cable of a large drill of this type will break and thus permit the drill to drop and not only cause damage to thedrill or work positioned beneath it but also endangers the lives of workmen handling the drill.

Another object of the invention is to so construct this safety attachment that it may be associated with a drill of a conventional construction and thus permit it to be used in connection with drills already in use.

Another object of the invention is to so construct this safety attachment that it will be of very simple construction and very easy to apply.

This invention is illustrated in the accompanying drawing wherein:

Figure 1 is a perspective view of a drill having the safety attachment connected therewith.

Fig. 2 is a view partially in section and partially in elevation showing the attachment connected with the drill carriage and held in the inoperative position by the supporting chain for the drill. v

This safety attachment is shown in use as applied to a large drill which is indicated in general by the numeral 10 and is of a conventional construction. This drill is further provided with a carriage 11 which is slidably mounted upon a track 12 and provided with the usual feeding mechanism 13 for engaging the teeth of the rack 16 and moving the carriage vertically upon the track. A supporting'chain 1a is connected with the carriage by means of the usual bolt 15 and this chain will be carried over suitable guides and having its second end connected with a counterbalancing weight so that the weight of the drill and carriage will be counterbalanced and thus the drill permitted to be easily moved vertically upon the track. The structure so far described is of a conventional construction and therefore has not been described in detail and it is to be understood that it is not desired to confine the invention to the specific drill shown as it can be used in connection with any device which is slidably mounted upon a track including a tooth bar or rack 16 for engagement by actuating mechanism for moving the track.

This attachment is in the form of a locking pawl 17 which is pivotally mounted between the bearing brackets 18 by means of the pin 19 so that it will be movable into and out of engagement with the teeth of the rack 16 It should be noted that the free end of the pawl is formed into a nose 17 which will fit between the teeth of the rack when the pawl is swung into engagement with the rack. These bearing brackets 18 are held in lace by suitable securing screws and it w1ll thus be seen that they can be easily applied to the carriage 11. The pawl 17 is provided with a handle extension 20 which extends upwardly and terminates in a head 21 for engaging the supporting chain let and thus holding the pawl 17 in the,

inoperative position shown. An actuating lever 22 extends from the upperend portion of the pawl at substantially right angles to the handle extension 20 and hasits free end portion provided with an opening 23 through which the upper end of the spring 24 may be passed to connect the spring with the actuating lever. This spring 24 has its lower end connected with the eye bolt 25 screwed into a threaded opening of the carriage and it will be readily seen that when the chain breaks, the contraction of the spring will cause the pawl to swing upon its pivot 19 and into engage ment with the rack 16 with the nose 17 fitting between the teeth of the rack. The carriage will thus be locked against downdevice longitudinally of the ward sliding movement and danger of an operator being injured by the drill falling upon him or danger of a drill or work being broken by the fallen drill prevented.

' When a new chain is put in place the drill will be moved upwardly by its shifting mechanism 13 and the pawl will thus be relieved from pressure and can be easily swung to an inoperative position with the head Qlpositioned to engage the chain. The chain will retain it in the inoperative position until the chainagain breaks.

What is claimed is:

The combination with a machine of the character described including a track, atoothed rack extending longitudinally of the I track and a carriage slidably mounted upon the track and including actuating mechanism for operatively engaging the teeth of the rack, of a suspending cable for the carriage extending in spaced relation to the track, a pawl pivotally mounted and having its free end portion formed into a nose for fitting between the teeth of the rack when in an operative position to hold the carriage against downward sliding movement, an abutment arm extending from the pawl and extending for engagement with the cable to hold the pawl against pivotal movement and retain the pawl in an inoperative position while the arm is in engagement with the cable, an actuating lever extending from the pawl, and means connected with the actuating lever for imparting movement to the lever and swinging the pawl into engagement with the rack when the abutment arm is out of engagement with the cable.

In testimony whereof I have hereunto set my hand.

HENRY V. JOHNSON.

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