1. Field of the Invention

This invention relates to pulleys for tight- ^' 5 ening and tensioning ropes or cords having a ratchet mechanism to permit retaining the same under tension, and more particularly, to such a mechanism which em¬ ploys a serrated pulley wheel or sheave to secure a cord or rope which is reeved therein. 0 2. Background Art

Various ratcheting mechanisms have been heretofore used to tighten belts for such applications as tie down straps for securing a load on a vehicle, for boat mooring or anchor systems, tree seats or 5 climbing aids, or other applications wherein it is desirable to be able to tighten a strap which subse¬ quently can easily be released. Summary of the Invention

The invention comprises an improvement in 0 the art of rope tightening mechanisms which utilize raised internal ridges or serrations in a pulley wheel or sheave. More particularly, the invention relates to such a device which contains serrations that extend radially from the base of the sheave on each surface 5 thereof but the ends of which are angled in order to

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grasp a rope or cord sheave thereover more firmly in one direction than the other. Specifically, in accor¬ dance with the present invention, the ridges or serrations on the sheave are formed so that they ex- tend radially from the axis thereof, but the radially outer ends thereof are angled in one direction. The direction of the angling is toward the direction of rotation of the sheave when a rope reeved thereon is tightened. In accordance with one embodiment of the invention, the cord or rope is tensioned by pulling thereon by hand. In another embodiment of the inven¬ tion the ratchet mechanism is provided with a pivoting lever in order to provide increased tensioning force on the rope or cord.

An important aspect and advantage of the present invention is the provision of a sheave which allows for easier release of the rope or cord but which still provides a secure gripping thereof in or- der to secure the tension of the rope. A further as¬ pect of the invention is to provide ridges or serrations which- are rounded and thus do not cause undue fraying of the rope or cord. A further aspect of the invention relates to the provision of a flat surface at the bottom of the sheave which does not cause undo wedging of the cord therein which prevents removal thereof.

Still a further aspect of the invention re¬ lates to providing a ratcheting sheave in which an end of a rope inserted thereon is accurately guided around the circumference of the sheave so that the entire circumference thereof comes into contact with the rope. Briefly summarized, the invention provides .a ratchet-type tensioning mechanism for a rope or cord having a rotatable sheave with faces having radially

extending serrations. A releasable ratchet mechanism permits rotation of the sheave in one direction but not the other. A plurality of serrations having al¬ ternating ridges arid valleys circumscribes the sheave, each of which has a radially extending portion extend¬ ing outwardly from the base of the sheave, the outer end of each of the ridges being angled in the direc¬ tion in which the sheave rotates when the ratchet mechanism is engaged, the ridges being positioned at regular intervals around the circumference of the sheave and being located so that a ridge on one face of the sheave faces a valley on the opposite face of the sheave. Preferably the ridges and valleys have rounded edges whereby a rope thereon does not become frayed. The device may include a ratcheting lever arm which engages the wheel and affords leveraged tensioning the rope.

Various other aspects and advantages of the invention will become apparent in connection with the accompanying drawings wherein: Drawings

Figure 1 is a perspective view of one em¬ bodiment of a rope tightening device of this inven¬ tion; Figure 2 is a perspective view showing the parts of Figure 1 disassembled for clarity;

Figure 3 is a top view of the tightening device of Figure 1 with the rope removed;

Figure 4 is a cross-sectional view of one- half of the sheave of Figure 3 taken along line 4-4;

Figure 5A is a cross-sectional view of the device of Figure 1 taken along line 5A-5A;

Figure 5B is another cross-sectional view taken along line 5A-5A of Figure 1 with the release mechanism in the released position;

Figure 6A is a cross-sectional view of the device of Figure 1 taken along line 6A-6A; and

Figure 6B is a further cross-sectional view taken along line 6A-6A but with the mechanism in the position to release the rope reeved therein.

Figure 7 is a perspective view of a differ¬ ent embodiment of a rope tightening device of this invention;

Figure 8 is a cross-sectional view through the longitudinal axis of the device of Figure 7 show¬ ing the lever arm in the open position; and,

Figure 9 is a cross-sectional view through the longitudinal axis of the device of Figure 7 show¬ ing the lever arm in the closed position. Detailed Description

Referring more specifically to the drawings, one form of tensioning mechanism 10, intended to be tightened by hand, is shown in Figures I-6B. Device 10 includes a housing 12 formed from divisible halves 11 and 13 which are attached together as seen in Fig¬ ure 2 by conventional mechanical fasteners. Rotatably held within housing 12 is a sheave 14. Sheave 1 , for ease of manufacture, is formed from halves 16 and iε. The inner face of each half of sheave 14 is provided with alternating ridges 17 and valleys 19. As best seen in Figure 3, the ridges 17 on one half of the sheave are aligned with a valleys 19 on the other half to thereby form a tortuous path for engagement of a rope or cord 15. One of the halves 16 and 18 is pro- vided with a threaded shaft 8 onto which a nut 9 can be threaded. The other half is preferably provided with a square or hexagonal head 20 integral therewith so that the parts can be assembled and disassembled using conventional wrenches or other tools. Shaft 8 can be provided with a configuration, such as a hexag-

onal cross-section, as illustrated, so that the halves of the sheave 14 will not rotate relative to each oth¬ er. By providing twelve ridges as seen in Figure 4 around the circumference of the sheave, a design is provided such that the respective ridges and valleys will be properly aligned regardless of the orientation of which the sheave half 16 is placed σn shaft 8. Housing 12 forms a chamber within which the sheave can rotate without being mounted on an axle connected to the chamber.

Opening 7 is of a restricted width such that the rope 15 is prevented thereby from passing around the outside of the sheave 14 thereby preventing wedg¬ ing of the rope between sheave 14 and housing 12. The opening also guides the rope 15 around sheave 14 to ensure maximum contact thereof with the sheave 1 .

The device is also provided with a ratchet mechanism 21 which is spring loaded by spring 22 to engage teeth 23 on a sprocket formed integrally with half 18 of the sheave. Projection 24 of ratchet mech¬ anism 21 is urged by spring 22 into the spaces between the teeth 23 of the sheave.

As seen in Figure 5, a rope 15 reeved on sheave 14 is permitted to move only in the direction of the arrow when projection 24 engages sprocket 23. However, when the ratchet mechanism is pivoted as shown in Figure 5B, the sheave is permitted to rotate in the counterclockwise direction thereby permitting loosening of rope 15. The end of the device opposite rope 15 is secured by appropriate means such as a hook 25 to a fastening means 27 to be placed under tension. Means 27 can be, for example, a strap on a load secured to a motor vehicle, a strap on a platform for attachment to a pole or tree, or, for example, a fastening device

for mooring watercraft.

As best seen in Figure 4, each of the ridges 17 is provided at the inner end with a radially ex¬ tending portion 30. Each of the ridges, however, is formed with a bend or "dog leg" 32 with the outer end 34 of each ridge 17 being angled in the direction in which the sheave rotates when the rope 15 is being tensioned. Another aspect of the invention is that the base of the sheave does not form a sharp "V" but rather has a flattened portion 35 which prevents rope 15 from being too tightly wedged in the sheave during tightening.

It has been found that the outer angled por¬ tions 34 of the ridges 17 tend to aggressively engage rope 15 to feed the same readily into the sheave when an end thereof is presented thereto as the sheave is rotated. However, since the inner portions 32 of the ridges are radially oriented, the rope can readily be loosened as seen in Figure 6A so the same can be re- moved without binding in the sheave. Flattened sur¬ face 35 also assists in such ready release of rope 15. In the alternate embodiment of Figures 7-9, a housing 52 in pivotally connected to a lever arm 54 by means of a pin 55. Also mounted for rotation on pin 55 is a sheave 56. Sheave 56 is provided on one side with a ratchet wheel 58 mounted integrally thereon. Each of the faces of sheave 56 is provided with serrations in the form of alternating ridges 60 and valleys 62 around the circumference thereof. As in the case of the previously described embodiment, ridges 60 are formed with an inner sections 61 that extend radi¬ ally outward from the hub of sheave 56 and outer sec¬ tions 63 that are angled in the direction that sheave 56 is rotated when rope 15 is being tightened. Lever arm 54 furnishes a means for applying

greater tension on rope 15 than generally can be ap¬ plied by hand. A ratchet latching plate 64 is provided in lever arm 54 to engage ratchet wheel 58. Plate 64 is urged against wheel 58 by means of spring 66. It 5. can be pushed by hand out of contact with wheel 58 in order to loosen rope 15 when desired. A second plate 68 is provided to prevent rotation of wheel58 while the rope 15 is being tightened by means of lever 54. Plate 68 is also urged against wheel 58 by means of a 0 spring, 70. Tabs 72 and 74 are provided on plates 64 and 68, respectively to provide a means to side the plates out of contact with wheel 58 in order to release rope 15. Suitable slot 73 can be provided in order to permit access to retract tab 72 when the le- 5 ver 54 is in the closed position of Figures 7 and 9.

In the preferred embodiment a wedge-shaped stripper element 76 is provided as seen in Figure 8. Stripper 76 is mounted on the end of housing 52 and has a curved end which engages the flat portion 57 at 0 the center of sheave 56 to provide an additional bear¬ ing surface which prevents movement or bending of axle 55 under heavy loads. It also provides a means tc positively strip the rope 15 from the sheave 56 sc that the device 50 does not become immobilized by such 5 wedging action.

While the invention has been described and illustrated in detail, it is to be understood that various modifications may be made within the spirit of the invention. Thus the scope thereof is limited only 0 by the terms of the following claims.