Title:
ROPE GRAB SAFETY DEVICE
United States Patent 3876036
Abstract:
A safety device comprising a bracket having means for attachment to a person working at elevated locations and for slidable mounting on a vertically extending safety line. A roller movable upwardly and downwardly in guide tracks on the bracket is so positioned in relation to a safety line extending through a channel on the bracket that upward movement of the roller in response to rapid downward sliding of the bracket along the safety line caused by the person's falling deflects the safety line laterally outwardly and wedges it against a friction surface on a safety line retainer member attached to the bracket above the roller.
US Patent References:
/1194062.html
Piche - August 1916 - 1194062
Scenery handling apparatus
Kuebler - July 1961 - 2991526
Safety line clamp
Murdock - April 1965 - 3177544
ROPE CLAMP
Postlehwait - April 1969 - 3437178
ROPE CLIMBING DEVICE
Hoffman - June 1974 - 3814210
/1194062.html
Piche - August 1916 - 1194062
Scenery handling apparatus
Kuebler - July 1961 - 2991526
Safety line clamp
Murdock - April 1965 - 3177544
ROPE CLAMP
Postlehwait - April 1969 - 3437178
ROPE CLIMBING DEVICE
Hoffman - June 1974 - 3814210
Application Number:
05/481389
Publication Date:
04/08/1975
Filing Date:
06/20/1974
View Patent Images:
Export Citation:
Assignee:
D.B. Enterprises, Inc. (Red Wing, MN)
Primary Class:
Other Classes:
182/192, 182/5, 188/65.200
International Classes:
A62B35/04; A62B35/00; A62B1/14
Field of Search:
182/5,18,6,7,11,191,192,193 188/65.2,65.1
Primary Examiner:
Machado, Reinaldo P.
Attorney, Agent or Firm:
Williamson, Bains & Moore
Claims:
What is claimed is
1. A rope grab, safety device for restrainably engaging a vertically extending safety line comprising:
2. A rope grab device as defined in claim 1 wherein:
3. A rope grab device as defined in claim 1 wherein:
4. A rope grab device as defined in claim 1 wherein:
5. A rope grab device as defined in claim 1 wherein:
6. A rope grab device as defined in claim 5 wherein:
7. A rope grab device as defined in claim 5 wherein:
8. A rope grab device as defined in claim 1 wherein:
9. A rope grab device for restrainably engaging a vertically extending safety line comprising:
10. A rope grab device as defined in claim 9 wherein:
11. A rope grab device as defined in claim 10 wherein:
1. A rope grab, safety device for restrainably engaging a vertically extending safety line comprising:
2. A rope grab device as defined in claim 1 wherein:
3. A rope grab device as defined in claim 1 wherein:
4. A rope grab device as defined in claim 1 wherein:
5. A rope grab device as defined in claim 1 wherein:
6. A rope grab device as defined in claim 5 wherein:
7. A rope grab device as defined in claim 5 wherein:
8. A rope grab device as defined in claim 1 wherein:
9. A rope grab device for restrainably engaging a vertically extending safety line comprising:
10. A rope grab device as defined in claim 9 wherein:
11. A rope grab device as defined in claim 10 wherein:
Description:
BRIEF SUMMARY OF THE INVENTION
This invention is directed to an improved rope grab, safety device which can be quickly and easily installed for sliding movement on a safety line to desired vertical positions of use, and which will automatically operate to firmly grab the safety line to catch and support a person to whom it is attached, if the person should fall from an elevated position along the safety line.
These basic objectives and advantages are realized by providing a mounting bracket with a safety line channel within which a roller is positioned for vertical movement so as to deflect a safety line extending through the channel laterally away from the vertical. A safety line retainer member which extends across the channel to hold the safety line therein is formed with a friction surface at its bottom end at a location above and laterally offset from the roller in the direction of safety line deflection. With the roller in contact with the safety line, downward movement of the mounting bracket along the safety line under free fall conditions will cause the roller to move upwardly to a position where it will deflect and wedge the safety line tightly against the aforesaid friction surface.
A particularly secure and positive gripping action of the device on a safety line is achieved by providing a second friction surface on the upper end of the aforesaid retainer member. This second friction surface is brought into frictional engagement with the safety line by the canting of the mounting bracket to an inclined position as a reaction to the wedging of the safety line between the roller and the bottom friction surface on the retainer member.
As a particularly advantageous feature of my improved rope grab device, I provide a second retainer member which is spaced vertically below the first, aforementioned retainer member to keep the safety line in contact with the roller, and to provide an open space between the two retainer members through which the safety line may be freely deflected by the roller. These two retainer members are preferably connected by a vertically extending hinge pin rotatably mounted on the bracket adjacent to the safety line channel so as to permit the two retainer members to be rotated together between open and closed positions relative to the safety line channel. This greatly facilitates the mounting of the bracket on a safety line, and the placement of the safety line within the bracket channel.
These and other objects and advantages of my invention, including the use of a built-in rope size gauge on the mounting bracket, will become readily apparent as the following description is read in conjunction with the accompanying drawings wherein like reference numerals have been used to designate like elements throughout the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the rope grab device of this invention;
FIG. 2 is a front, elevation view of the rope grab device of FIG. 1;
FIG. 3 is an end view of the rope grab device;
FIG. 4 is a top, plan view of the rope grab device;
FIG. 5 is a vertical, section view of the rope grab device taken along lines 5--5 of FIG. 3; and
FIG. 6 is a view of a rope size gauge which is provided on the device.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, I have shown in FIG. 1 a perspective view of a preferred embodiment of my improved rope grab device wherein the mounting bracket is generally indicated by reference numeral 1. Mounting bracket 1 is comprised of a pair of upright, side plates 2 and 4 connected by a spacer plate 6 having a vertically extending segment 6a. With mounting bracket 1 in its upright position of use as shown in FIG. 1, spaced apart, vertically extending wall segments 2a and 4a on the forward ends of side plates 2 and 4 define therebetween a vertical channel through which a safety line 8 extends. Safety line 8 may be a rope, cable or other type of strong line which is normally supported in a vertical position on a building or other upright structure on which a person may be working at an elevated level. Safety line or rope 8 is guided and contained within the channel defined between bracket wall segments 2a and 4a in the manner shown in FIGS. 1, 4 and 5.
Guide tracks, preferably in the form of vertical slots 10 and 12 are formed in wall segments 2a and 4a. These guide tracks serve to guide and support a roller 14 for vertical movement up and down along the safety line channel. Roller 14 extends between opposed, parallel guide tracks 10 and 12 in the manner shown with its end stub shafts 16 and 18 extending through the guide track slots 10 and 12. Stop collars 14a and 14b on the opposite ends of roller 14 bear against the inside faces of wall segments 2a and 4a and serve to guide and position roller 14 between these wall segments. Roller 14 is preferably knurled to improve its frictional engagement with safety line 8, with which it is in contact. Roller 14 is positioned in the safety line guide channel between wall segments 2a and 4a at a location where it will be in the free hanging, vertical path of safety line 8. Thus, roller 14 will normally deflect safety line 8 laterally outwardly, away from the vertical in the manner shown in FIG. 5.
For the purpose of containing safety line 8 within the mounting bracket channel, and to provide friction surfaces to grip safety line 8, I provide a retainer member 20 on the upper end of mounting bracket 1. Upper, retainer member 20 preferably takes the form of an elongated, cylindrical segment as shown, and serves to contain safety line 8 within the aforesaid channel on bracket 1 when it is positioned across the safety line channel on the forward ends of wall segments 2a and 4a as shown in FIGS. 2, 3 and 4. Retainer member 20 is oriented vertically in a direction parallel to the roller guide slots 10 and 12 on the forward ends of wall segments 2a and 4a.
For a purpose hereinafter explained, friction surfaces 20a and 20b are formed on the bottom and top ends of retainer member 20. These two friction surfaces are preferably of arcuate shape and flare outwardly away from the safety line guide channel in the manner shown most clearly in FIG. 5.
Retainer member 20 is preferably hingedly attached to the forward end of wall segment 4a by means of a first pair of vertically spaced hinge sleeves 22a and 22b affixed, as by welding, to one side thereof. A second pair of vertically spaced hinge sleeves 24a and 24b are attached to the opposite side of retainer member 20. These hinge sleeves cooperate with a pair of hinge sleeves 26 and 28 affixed to the forward ends of wall segments 2a and 4a to permit the opening and closing movement of retainer member 20 with respect to the safety line channel formed between wall segments 2a and 4a. This is accomplished by an elongated hinge pin 30 which extends through fixed hinge sleeve 28 and is secured to retainer member hinge sleeves 22a and 22b for rotation therewith. Hinge pin 30 extends vertically adjacent to the safety line channel on mounting bracket 1 and is rotatably supported at its lower end within a hinge sleeve 32 affixed to the bottom of wall segment 4a. A second retainer member in the form of a hook-like segment of a ring 34 is formed on the bottom end of hinge pin 30 for rotation therewith. Lower retainer member 34 functions in its closed position as shown in FIGS. 2, 3 and 5 to hold safety line 8 in contact with roller 14. Lower, safety line retainer member 34 is vertically spaced downwardly from upper retainer member 20 below its friction surface 20a to define a completely open space therebetween opposite roller 14 through which safety line 8 may be freely deflected laterally by roller 14 as it moves upwardly and downwardly in the safety line channel of mounting bracket 1.
For the purpose of holding upper and lower retainer members 20 and 34 in their closed positions across the safety line channel of bracket 1, I provide a locking pin 36 which may be removably inserted through sleeves 24a, 26 and 24b as shown in FIGS. 2 and 3. A pull ring 38 on the top end of lock pin 36 permits this pin to be easily removed by pulling it upwardly as illustrated in FIG. 1, after which retainer members 20 and 34 may be rotated with hinge pin 30 to the open position shown in FIG. 1. Chain 40 connected between pull ring 38 and a retainer ring 42 affixed to side plate 2 secures lock pin 36 to mounting bracket 1.
A lanyard 34 is used to attach mounting bracket 1 to a workman by means of a belt buckle or coupling, or other appropriate means in a manner well known in the art. Lanyard 34 is looped at its inner end, as illustrated in phantom line in FIG. 5 and secured to mounting bracket 1 by means of a pin 46 extending therethrough. A roll pin or cotter pin 48 shown in FIG. 4 holds lanyard pin 46 in place after it has been inserted through the looped end of lanyard 34 and through aligned apertures in side plates 2 and 4.
A rope size gauge plate or label 50 is affixed to the outer face of side plate 2, and has an indicator mark in the form of a dot 52 thereon. This size gauge is used in a manner hereinafter explained to check the size of a rope for safe, satisfactory operation with my improved rope grab device.
In operation lanyard 44 is affixed to a workman, and bracket 1 is mounted on safety line 8. With lock pin 36 removed and retainer members 20 and 34 swung to the open position shown in FIG. 1, this latter step is readily accomplished by simply abutting mounting bracket 1 against safety line 8 to position the safety line within the guide channel formed between wall segments 2a and 4a. Retainer members 20 and 34 are then rotated with hinge pin 30, to which they are connected as a unitary assembly to their closed positions across the safety line channel as shown in FIGS. 2, 3 and 4. Lock pin 36 is then inserted in place through hinge sleeves 24a, 26 and 24b to secure these retainer members in their closed positions. It will be appreciated that hinge sleeves 24a and 24b cooperate with stationary hinge sleeve 26 and removable lock pin 36 to provide releasable locking means for the retainer member assembly.
With bracket 1 so mounted on safety line 8 in the upright position shown, roller 14 will be in the normal, vertical path of safety line 8, and will deflect it laterally. As illustrated in FIG. 5, with roller 14 in its downward, release position, safety line 8 will assume the shape shown in phantom lines wherein it will be deflected laterally from the vertical, but will not be urged tightly against either bottom or top friction surfaces 20a and 20b of retainer member 20.
In order to ensure that safety line 8 is of a satisfactory size for safe operation with my improved rope grab device, roller 14 is moved upwardly within guide slots 10 and 12 to the point where it urges safety line 8 against bottom friction surface 20a of retainer member 20. Indicator dot 52 is so positioned on gauge plate 50 that if roller 14 can be moved upwardly beyond this indicator dot as it urges rope or safety line 8 against friction surface 20a, the safety line is undersized. It will be appreciated that a safety line of a certain minimum diameter is required in order to ensure that roller 8 will be able to wedge the safety line against friction surface 20a when it reaches the top of guide slots 10 and 12.
Mounting bracket 1 can be easily moved upwardly and downwardly on safety line 8 to a desired vertical position by a workman to which it is attached by simply moving roller 14 to the bottom end of guide slots 10 and 12. This releases all frictional contact of surface 20a with safety line 8, and permits the mounting bracket 1 to be freely moved up and down on the safety line. It will thus be appreciated that the particular hinged mounting of retainer members 20 and 34 on bracket 1, and the positioning and operation of roller 14 relative to the bottom friction surface 20a on retainer 20, permits bracket 1 to be initially mounted at any desired vertical location along a safety line 8, and also to be adjusted vertically up and down on the safety line subsequently without opening retainer members 20 and 34 or removing bracket 1 from the safety line.
It is of course understood that the primary function of my improved rope grab device is to quickly and effectively catch and support a person attached to mounting bracket 1 in the event of an accidental fall. If the person falls, mounting bracket 1 travels rapidly down safety line 8 thereby causing roller 14 to move upwardly in guide slots 10 and 12. This upward, reaction movement of roller 14 is assured by maintaining contact between roller 14 and safety line 8. Such contact is established and maintained by positioning roller 14 within the vertical path of safety line 8, and by utilizing lower retainer member 34 as shown to hold safety line 8 against the roller. As roller 14 approaches upper retainer member 20 under free fall conditions of mounting bracket 1 downwardly along safety line 8, it restricts safety line 8 by wedging it against bottom friction surface 20a on retainer member 20. In FIG. 5 I have illustrated in dotted lines the position to which rope 8 will be deflected by roller 14 as it reaches the upper end of guide slots 10 and 12. In such a position of roller 14 and rope 8, rope 8 will be tightly wedged between the roller and friction surface 20a, thereby stopping the downward travel of mounting bracket 1 along safety line or rope 8. The rounded, downwardly and outwardly flared shape of friction surface 20a provides a friction surface against which safety line 8 may be wedged by the upward movement of roller 14 without damage to the rope. The aforesaid wedging action against safety line 8 is assured by locating friction surface 20a above roller 14 at a location laterally offset therefrom in the direction of deflection of safety line 8.
The sudden gripping of safety line 8 between roller 14 and friction surface 20a will cause mounting bracket 1 to cant or rotate from the vertical substantially about the gripping points of roller 14 and friction surface 20a. In FIG. 5 I have illustrated in dotted lines the inclined positions to which retainer member 20 and bracket spacer plate segment 6a will be rotated by the stopping action of roller 14. The canting of mounting plate 1 in this manner will bring upper friction surface 20b of retainer member 20 into contact with rope 8, thereby producing additional frictional drag on the rope. At this point, rope or safety line 8 will generally assume the position shown in dotted lines in FIG. 5. This combination of wedging action by roller 14 against friction surface 20a, and frictional drag produced by upper friction surface 20b provides a very positive, secure gripping action of the rope grab device on safety line 8.
I anticipate that various modifications can be made in the size, shape and structural arrangement of the component parts of my improved rope grab device disclosed herein, without departing from the spirit and scope of my invention as defined by the following claims.
This invention is directed to an improved rope grab, safety device which can be quickly and easily installed for sliding movement on a safety line to desired vertical positions of use, and which will automatically operate to firmly grab the safety line to catch and support a person to whom it is attached, if the person should fall from an elevated position along the safety line.
These basic objectives and advantages are realized by providing a mounting bracket with a safety line channel within which a roller is positioned for vertical movement so as to deflect a safety line extending through the channel laterally away from the vertical. A safety line retainer member which extends across the channel to hold the safety line therein is formed with a friction surface at its bottom end at a location above and laterally offset from the roller in the direction of safety line deflection. With the roller in contact with the safety line, downward movement of the mounting bracket along the safety line under free fall conditions will cause the roller to move upwardly to a position where it will deflect and wedge the safety line tightly against the aforesaid friction surface.
A particularly secure and positive gripping action of the device on a safety line is achieved by providing a second friction surface on the upper end of the aforesaid retainer member. This second friction surface is brought into frictional engagement with the safety line by the canting of the mounting bracket to an inclined position as a reaction to the wedging of the safety line between the roller and the bottom friction surface on the retainer member.
As a particularly advantageous feature of my improved rope grab device, I provide a second retainer member which is spaced vertically below the first, aforementioned retainer member to keep the safety line in contact with the roller, and to provide an open space between the two retainer members through which the safety line may be freely deflected by the roller. These two retainer members are preferably connected by a vertically extending hinge pin rotatably mounted on the bracket adjacent to the safety line channel so as to permit the two retainer members to be rotated together between open and closed positions relative to the safety line channel. This greatly facilitates the mounting of the bracket on a safety line, and the placement of the safety line within the bracket channel.
These and other objects and advantages of my invention, including the use of a built-in rope size gauge on the mounting bracket, will become readily apparent as the following description is read in conjunction with the accompanying drawings wherein like reference numerals have been used to designate like elements throughout the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the rope grab device of this invention;
FIG. 2 is a front, elevation view of the rope grab device of FIG. 1;
FIG. 3 is an end view of the rope grab device;
FIG. 4 is a top, plan view of the rope grab device;
FIG. 5 is a vertical, section view of the rope grab device taken along lines 5--5 of FIG. 3; and
FIG. 6 is a view of a rope size gauge which is provided on the device.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, I have shown in FIG. 1 a perspective view of a preferred embodiment of my improved rope grab device wherein the mounting bracket is generally indicated by reference numeral 1. Mounting bracket 1 is comprised of a pair of upright, side plates 2 and 4 connected by a spacer plate 6 having a vertically extending segment 6a. With mounting bracket 1 in its upright position of use as shown in FIG. 1, spaced apart, vertically extending wall segments 2a and 4a on the forward ends of side plates 2 and 4 define therebetween a vertical channel through which a safety line 8 extends. Safety line 8 may be a rope, cable or other type of strong line which is normally supported in a vertical position on a building or other upright structure on which a person may be working at an elevated level. Safety line or rope 8 is guided and contained within the channel defined between bracket wall segments 2a and 4a in the manner shown in FIGS. 1, 4 and 5.
Guide tracks, preferably in the form of vertical slots 10 and 12 are formed in wall segments 2a and 4a. These guide tracks serve to guide and support a roller 14 for vertical movement up and down along the safety line channel. Roller 14 extends between opposed, parallel guide tracks 10 and 12 in the manner shown with its end stub shafts 16 and 18 extending through the guide track slots 10 and 12. Stop collars 14a and 14b on the opposite ends of roller 14 bear against the inside faces of wall segments 2a and 4a and serve to guide and position roller 14 between these wall segments. Roller 14 is preferably knurled to improve its frictional engagement with safety line 8, with which it is in contact. Roller 14 is positioned in the safety line guide channel between wall segments 2a and 4a at a location where it will be in the free hanging, vertical path of safety line 8. Thus, roller 14 will normally deflect safety line 8 laterally outwardly, away from the vertical in the manner shown in FIG. 5.
For the purpose of containing safety line 8 within the mounting bracket channel, and to provide friction surfaces to grip safety line 8, I provide a retainer member 20 on the upper end of mounting bracket 1. Upper, retainer member 20 preferably takes the form of an elongated, cylindrical segment as shown, and serves to contain safety line 8 within the aforesaid channel on bracket 1 when it is positioned across the safety line channel on the forward ends of wall segments 2a and 4a as shown in FIGS. 2, 3 and 4. Retainer member 20 is oriented vertically in a direction parallel to the roller guide slots 10 and 12 on the forward ends of wall segments 2a and 4a.
For a purpose hereinafter explained, friction surfaces 20a and 20b are formed on the bottom and top ends of retainer member 20. These two friction surfaces are preferably of arcuate shape and flare outwardly away from the safety line guide channel in the manner shown most clearly in FIG. 5.
Retainer member 20 is preferably hingedly attached to the forward end of wall segment 4a by means of a first pair of vertically spaced hinge sleeves 22a and 22b affixed, as by welding, to one side thereof. A second pair of vertically spaced hinge sleeves 24a and 24b are attached to the opposite side of retainer member 20. These hinge sleeves cooperate with a pair of hinge sleeves 26 and 28 affixed to the forward ends of wall segments 2a and 4a to permit the opening and closing movement of retainer member 20 with respect to the safety line channel formed between wall segments 2a and 4a. This is accomplished by an elongated hinge pin 30 which extends through fixed hinge sleeve 28 and is secured to retainer member hinge sleeves 22a and 22b for rotation therewith. Hinge pin 30 extends vertically adjacent to the safety line channel on mounting bracket 1 and is rotatably supported at its lower end within a hinge sleeve 32 affixed to the bottom of wall segment 4a. A second retainer member in the form of a hook-like segment of a ring 34 is formed on the bottom end of hinge pin 30 for rotation therewith. Lower retainer member 34 functions in its closed position as shown in FIGS. 2, 3 and 5 to hold safety line 8 in contact with roller 14. Lower, safety line retainer member 34 is vertically spaced downwardly from upper retainer member 20 below its friction surface 20a to define a completely open space therebetween opposite roller 14 through which safety line 8 may be freely deflected laterally by roller 14 as it moves upwardly and downwardly in the safety line channel of mounting bracket 1.
For the purpose of holding upper and lower retainer members 20 and 34 in their closed positions across the safety line channel of bracket 1, I provide a locking pin 36 which may be removably inserted through sleeves 24a, 26 and 24b as shown in FIGS. 2 and 3. A pull ring 38 on the top end of lock pin 36 permits this pin to be easily removed by pulling it upwardly as illustrated in FIG. 1, after which retainer members 20 and 34 may be rotated with hinge pin 30 to the open position shown in FIG. 1. Chain 40 connected between pull ring 38 and a retainer ring 42 affixed to side plate 2 secures lock pin 36 to mounting bracket 1.
A lanyard 34 is used to attach mounting bracket 1 to a workman by means of a belt buckle or coupling, or other appropriate means in a manner well known in the art. Lanyard 34 is looped at its inner end, as illustrated in phantom line in FIG. 5 and secured to mounting bracket 1 by means of a pin 46 extending therethrough. A roll pin or cotter pin 48 shown in FIG. 4 holds lanyard pin 46 in place after it has been inserted through the looped end of lanyard 34 and through aligned apertures in side plates 2 and 4.
A rope size gauge plate or label 50 is affixed to the outer face of side plate 2, and has an indicator mark in the form of a dot 52 thereon. This size gauge is used in a manner hereinafter explained to check the size of a rope for safe, satisfactory operation with my improved rope grab device.
In operation lanyard 44 is affixed to a workman, and bracket 1 is mounted on safety line 8. With lock pin 36 removed and retainer members 20 and 34 swung to the open position shown in FIG. 1, this latter step is readily accomplished by simply abutting mounting bracket 1 against safety line 8 to position the safety line within the guide channel formed between wall segments 2a and 4a. Retainer members 20 and 34 are then rotated with hinge pin 30, to which they are connected as a unitary assembly to their closed positions across the safety line channel as shown in FIGS. 2, 3 and 4. Lock pin 36 is then inserted in place through hinge sleeves 24a, 26 and 24b to secure these retainer members in their closed positions. It will be appreciated that hinge sleeves 24a and 24b cooperate with stationary hinge sleeve 26 and removable lock pin 36 to provide releasable locking means for the retainer member assembly.
With bracket 1 so mounted on safety line 8 in the upright position shown, roller 14 will be in the normal, vertical path of safety line 8, and will deflect it laterally. As illustrated in FIG. 5, with roller 14 in its downward, release position, safety line 8 will assume the shape shown in phantom lines wherein it will be deflected laterally from the vertical, but will not be urged tightly against either bottom or top friction surfaces 20a and 20b of retainer member 20.
In order to ensure that safety line 8 is of a satisfactory size for safe operation with my improved rope grab device, roller 14 is moved upwardly within guide slots 10 and 12 to the point where it urges safety line 8 against bottom friction surface 20a of retainer member 20. Indicator dot 52 is so positioned on gauge plate 50 that if roller 14 can be moved upwardly beyond this indicator dot as it urges rope or safety line 8 against friction surface 20a, the safety line is undersized. It will be appreciated that a safety line of a certain minimum diameter is required in order to ensure that roller 8 will be able to wedge the safety line against friction surface 20a when it reaches the top of guide slots 10 and 12.
Mounting bracket 1 can be easily moved upwardly and downwardly on safety line 8 to a desired vertical position by a workman to which it is attached by simply moving roller 14 to the bottom end of guide slots 10 and 12. This releases all frictional contact of surface 20a with safety line 8, and permits the mounting bracket 1 to be freely moved up and down on the safety line. It will thus be appreciated that the particular hinged mounting of retainer members 20 and 34 on bracket 1, and the positioning and operation of roller 14 relative to the bottom friction surface 20a on retainer 20, permits bracket 1 to be initially mounted at any desired vertical location along a safety line 8, and also to be adjusted vertically up and down on the safety line subsequently without opening retainer members 20 and 34 or removing bracket 1 from the safety line.
It is of course understood that the primary function of my improved rope grab device is to quickly and effectively catch and support a person attached to mounting bracket 1 in the event of an accidental fall. If the person falls, mounting bracket 1 travels rapidly down safety line 8 thereby causing roller 14 to move upwardly in guide slots 10 and 12. This upward, reaction movement of roller 14 is assured by maintaining contact between roller 14 and safety line 8. Such contact is established and maintained by positioning roller 14 within the vertical path of safety line 8, and by utilizing lower retainer member 34 as shown to hold safety line 8 against the roller. As roller 14 approaches upper retainer member 20 under free fall conditions of mounting bracket 1 downwardly along safety line 8, it restricts safety line 8 by wedging it against bottom friction surface 20a on retainer member 20. In FIG. 5 I have illustrated in dotted lines the position to which rope 8 will be deflected by roller 14 as it reaches the upper end of guide slots 10 and 12. In such a position of roller 14 and rope 8, rope 8 will be tightly wedged between the roller and friction surface 20a, thereby stopping the downward travel of mounting bracket 1 along safety line or rope 8. The rounded, downwardly and outwardly flared shape of friction surface 20a provides a friction surface against which safety line 8 may be wedged by the upward movement of roller 14 without damage to the rope. The aforesaid wedging action against safety line 8 is assured by locating friction surface 20a above roller 14 at a location laterally offset therefrom in the direction of deflection of safety line 8.
The sudden gripping of safety line 8 between roller 14 and friction surface 20a will cause mounting bracket 1 to cant or rotate from the vertical substantially about the gripping points of roller 14 and friction surface 20a. In FIG. 5 I have illustrated in dotted lines the inclined positions to which retainer member 20 and bracket spacer plate segment 6a will be rotated by the stopping action of roller 14. The canting of mounting plate 1 in this manner will bring upper friction surface 20b of retainer member 20 into contact with rope 8, thereby producing additional frictional drag on the rope. At this point, rope or safety line 8 will generally assume the position shown in dotted lines in FIG. 5. This combination of wedging action by roller 14 against friction surface 20a, and frictional drag produced by upper friction surface 20b provides a very positive, secure gripping action of the rope grab device on safety line 8.
I anticipate that various modifications can be made in the size, shape and structural arrangement of the component parts of my improved rope grab device disclosed herein, without departing from the spirit and scope of my invention as defined by the following claims.