US3765652A

US3765652A - Cable hoist

Info

Publication number: US3765652A
Application number: US00132735A
Authority: US
Inventors: A Janik
Original assignee: Emerson Electric Co
Current assignee: Emerson Electric Co
Priority date: 1971-04-09
Filing date: 1971-04-09
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16

Abstract

A cable hoist is provided which has a frame and a drum in the frame to which a cable is attached and a ratchet wheel secured to the drum. A handle mounted on the frame carries a ratchet pawl for engagement with the ratchet wheel. A holding pawl mounted in the frame cooperates with the ratchet pawl and wheel to enable the drum to be ratcheted and wind up the cable. A disc is disposed alongside the ratchet wheel and has notches in it which correspond to a lesser number of teeth than are on the ratchet wheel. The holding pawl can be moved laterally to cause it to extend over the disc as well as the ratchet wheel and the disc will hold the holding pawl out of engagement with some of the teeth of the ratchet wheel to allow the cable to unwind from the drum under control of the handle several teeth at a time.

Description

United States Patent 91 Janik [451 Oct. 16, 1973 1 CABLE HOIST [75 Inventor: Anton J. Janik, North Ridgeville.

Ohio

[73 l Assignee: Emerson Electric Co., St. Louis, Mo.

[22] Filed: Apr. 9, 1971 21 Appl. No.1 132,735

[52] US. Cl. 254/167, 254/186 l-lC, 74/155 [51] Int. Cl B66d 1/00 [58] Field of Search 254/167, 164, 186 HC; 74/148, 149, 154, 155

[56] 4 References Cited UNITED STATES PATENTS 3,198,487 8/1965 Cox 254/167 3,163,399 12/1964 Skerry 254/167 2,443,744 6/1948 Mohnkern 74/154 X 1,246,555 11/1917 Crist 74/149 Primary Examiner-Evon C. Blunk Assistant ExaminerMerle F. Maffei Attorney-J. D. Douglass [57] ABSTRACT A cable hoist is provided which has a frame and a drum in the frame to which a cable is attached and a ratchet wheel secured to the drum. A handle mounted on the frame carries a ratchet pawl for engagement with the ratchet wheel. A holding pawl mounted in the frame cooperates with the ratchet pawl and wheel to enable the drum to be ratcheted and wind up the cable. A disc is disposed alongside the ratchet wheel and has notches in it which correspond to a lesser number of teeth than are on the ratchet wheel. The holding pawl can be moved laterally to cause it to extend over the disc as well as the ratchet wheel and the disc will hold the holding pawl out of engagement with some of the teeth of the ratchet wheel to allow the cable to unwind from the drum under control of the handle several teeth at a time.

2 Claims, 3 Drawing Figures Patented Oct. 16, 1973 INVENTOR.

CABLE HOIST This invention relates to improvements in hoists and particularly to an improved hand operated cable hoist.

Cable hoists usually have a drum disposed in a frame to which drum a cable is attached. A handle and ratchet means mounted on the frame is used for rotating the drum to raise or pull a load, the frame being attached to a support and the end of the cable to the load. In such devices the raising and lowering, which are terms that will also be used for pulling or releasing, is effected by reciprocating the handle. The ratchet means includes a ratchet wheel secured to or a part of the drum and a ratchet pawl carried by the handle for rotating the drum forward and a holding pawl for holding the drum when the handle is reciprocated backward to obtain a new moving engagement with the ratchet wheel. In such devices, although the load may be raised rapidly, the lowering of the load is usually effected one tooth at a time which is time-consuming. Although devices have been proposed whereby the load may be lowered more than one tooth at a time, as shown in U.S. Pat. No. 3,198,487, such devices have been expensive and complicated to make, containing many small parts.

In addition, the more complicated devices with the many parts were subject to breakage where if even one small part broke the device was rendered inoperative. This usually occurred in the field where no replacement was available or repair was impractical. In addition these devices which are subjected to very rough usage, could be made inoperable due to dirt which entered between the parts.

The present invention contemplates an apparatus wherein the number of parts are greatly reduced and is thus capable of being produced economically. In addition, the lowering operation may be performed rapidly by a mechanism greatly simplified over the prior art and with less tendency to become inoperative in the presence of foreign matter such as soil or dirt.

Still other advantages of the invention and the invention itself will become more apparent from the following description of an embodiment thereof which is illustrated by the accompanying drawings and forms a part of this specification.

In the drawings:

FIG. 1 is a side elevational view of the hoist of the invention with some parts broken away to show the underlying structure and other parts otherwise hidden shown by dotted lines;

FIG. 2 is a fragmentary view taken from the line 22 of FIG. 1; and

FIG. 3 is a fragmentary plan view taken from the line 3-3 of FIG. 1.

-The device consists of a generally rectangular frame which provides a pair of side members 10a connected together in spaced parallel relation by curved end parts 10b and 100. The part 10b has a hoist hook l2 swivably carried therein whereby it may be connected to a support or to a load.

A cable drum or spool 16 is rotatably supported in the frame on an axle 18 extending through and projecting beyond bosses 10d on the side members 10a on opposite sides of the frame. The cable drum has a side flange or end bell 16a at one end and a ratchet wheel 16b at the other end, the cable C being secured to the drum and wound or unwound on or from the drum between the flange and wheel depending on whether the drum is being turned or released for raising or lowering a load, in the usual manner for devices of this type.

The ratchet wheel includes the part 16b which has the usual ratchet teeth 16c and juxtaposed and secured to it a ratchet wheel disc 16d. The radius of the ratchet disc is at least coextensive with or slightly larger than that of the ratchet wheel and thus extends beyond the notches defined by the ratchet wheel teeth and preferably slightly outward of the teeth crests except at certain places around its periphery where it is provided with notches 16e that correspond in profile to that of the notch defined by the contour of the teeth between the crests of two succeeding teeth and are coincident therewith and are of a lesser number than there are teeth on the ratchet wheel. Although the number of notches in the disc may vary, it is preferred that they bear a definite relationship to the number of teeth in the ratchet wheel and which, in this case, is determined by, the size of the ratchet wheel, the number of teeth, and, the throw of the ratchet handle. In the drawings as illustrated the ratio as being 1:4, that is, for a ratchet wheel with 16 teeth the ratchet disc would have four notches. The disc and wheel may be made as one part or in two parts secured together in any suitable manner since the load on the disc will be negligible.

The ratchet handle 20 is removably secured to a yoke 22 journalled on the axle l8 outwardly of the frame which yoke carries a ratchet pawl 24 journalled on a pin 26 in the yoke. The pawl is of the type which is held by a spring into engagement with the ratchet wheel for the load raising operation and which spring can be moved to hold the pawl out of engagement with the ratchet wheel for the load lowering operation, which expedient is well known in the art and an example of which is shown in U.S. Pat. No. 2,816,733. In this instance a spring 25 has a bent end captured in the yoke and extends across the yoke between a pair of lugs 24a on the pawl. The end of the spring extends through an opening of a bell crank lever 27 whereby the end of the spring may be moved to bring pressure on either one of the lugs 24a of the ratchet pawl to hold it resiliently into or out of engagement with the ratchet wheel. The end 24c of the pawl is contoured to engage with any one of the radially extending faces of the teeth. A laterally extending boss 24b is provided on the'outer edge of the pawl, which as will later appear engages with a holding pawl release member for lowering purposes as will later be described.

As is also well known in the art the ratchel pawl operates in conjunction with a holding pawl, the holding pawl ratcheting over the teeth of the ratchet wheel as the ratchet pawl advances the drum to wind up the cable and holds the drum when the ratchet wheel is moved back to its starting position to obtain a new bite on the ratchet wheel.

A shaft 30 having a headed end 30b, as best shown in FIG. 2, is disposed in the side members of the frame being held in place by a pair of C rings 32 disposed in grooves in the shaft on opposite sides of the lower one of the frame members which is provided with a bored boss at this point. The head is disposed in an enlarged opening in the other side frame member.

The holding pawl 36 has an end portion 36b shaped to engage with any one of the ratchet wheel teeth and is disposed on a hub 36a rotatably journalled on the shaft 30. Extending from the hub in the opposite direction from the pawl end 36b is an arm 360 which extends beyond the confinesof the frame where it may be operated by hand to move the pawl out of engagement with the teeth when it is desired to free the wheel to pull out the cable. The pawl 36b is normally held in spring pressed engagement with the ratchet teeth by a helical spring 38, of open convolutions, disposed about the shaft. The convolutions of the spring are also in spaced relation to the shaft and the ends are bent at right angles outwardly with the end 38a engaged in an aperture in the pawl and the other end 38b engaged in the frame. The spring 38 is also under compression between the frame and paw] and thus urges the pawl inwardly from the upper frame to a position where it normally only engages with the teeth of the ratchet wheel.

The other end of the hub, the downward side as viewed in FIG. 2, has a helical pawl release spring 40 of closed convolutions disposed on the hub one end 40a of which is bent outward at right angles and extends into a hole in the pawl. The other end 40b of this spring projects toward the cable drum, being disposed to be engaged by the ratchet pawl at the end of the stroke of the ratchet lever to release the holding pawl. The spring is held in place by a lock ring 42 disposed in a groove in the hub and extending outwardly from the hub surface to form a flange on the hub.

Next, the end of the hub beyond the lock ring and downward as viewed in FIG. 2, is formed with a V notch 40c extending across the end of the hub through the axis. A holding pawl shift cam and lever 46 is rotatably disposed on the shaft 30 and includes a hub 460 having a projection or cam surface 46b complementary to the V" notch 40b and an operating handle 46c. This member is held in contact with the holding pawl assembly by a compression spring 48 disposed around the shaft with one end engaged with the holding pawl and the other end in engagement with the inner of the C rings 32. The length of the spring 48 is such that it positions the shift cam member and it in turn the holding pawl so that the ratchet engaging end 36b of the holding pawl is disposed opposite to the ratchet wheel 16b just inward of the disc 16d. The holding pawl actuating spring 38 between the holding pawl and the frame requires less compression force to force the convolutions together than the spring 48. Thus, when the cam lever 460 is moved, the cam projection 46b rides up one of the sides of the V" notch 40b and causes the holding pawl to be moved toward the upper frame, if the end 36b happens to be lined up with one of the notches 16a, which coincides with a tooth, and the holding pawl moves over until the end is over the disc 16d as well as the ratchet wheel.

The cam lever can be moved through an arc sufficient to cause the projection 46b to ride on the high part of the hub beyond the V notch and maintain the holding pawl in its laterally shifted position where it is opposite to both the disc and the ratchet wheel.

Should the cam be moved at a time when a notch in the disc did not happen to be lined up with the pawl, the spring 48 will be compressed, the cam lever assembly moving downward as viewed in FIG. 2. Then subse quently when the ratchet handle is moved to move the ratchet wheel the holding pawl will snap over into position opposite the disc and ratchet wheel when a corresponding notch and tooth arrive in alignment with the end of the holding pawl.

In operation, when it is desired to raise a load, the cable can be unrolled from the drum by moving the holding pawl handle 360 to release the holding pawl 36b from engagement with the ratchet wheel teeth. Then the hook is secured to a support and the cable to a load or vice versa and the holding pawl released to return to its holding position. When the handle 20 is moved counterclockwise, as viewed in FIG. 1, it being assumed that the ratchet pawl 24 is in the position shown, the ratchet wheel is moved, along with the drum, winding up the cable. During the winding up stroke the holding pawl ratchets over the teeth of the ratchet wheel and prevents the wheel from turning in the unwinding direction on the return stroke of the handle. The reciprocating motion of the handle is continued until the load is raised or pulled the desired amount.

When it is desired to lower a load or release tension on the cable, the ratchet pawl may be disengaged from the ratchet wheel by moving the lever 27 to the lowering position at which time the spring that held the ratchet pawl in engagement with the ratchet wheel is now moved to engage the opposite lug 24a on the ratchet pawl and hold it resiliently out of engagement with the ratchet wheel. The load may now be lowered one tooth at a time, by moving the ratchet handle.

The above is effected by the fact that the ratchet pawl being out of engagement with the wheel the ratchet handle can be moved to bring the ratchet handle toward the holding pawl for a full stroke at which time the ratchet wheel is not moved. As the ratchet pawl approaches the holding pawl, the laterally extended boss 24b on the ratchet pawl engages with the end portion 40b of the holding pawl release spring. The spring is sufficiently stiff that it overcomes the tension exerted by the ratchet pawl spring 25 and causes the pawl to move inward, eventually causing it to engage with a tooth of the ratchet wheel. The tooth engaged is the one just ahead of the tooth engaged by the holding pawl. Since the spring 40 is now under tension because of its engagement by the ratchet pawl, when the ratchet pawl starts to move the ratchet wheel to move the tooth engaged by the holding pawl slightly beyond the holding pawl, the spring 40 will rotate the holding pawl outward away from the tooth against the pressure of the spring 38. The pull on the drum being clockwise, the handle may now be moved clockwise, the ratchet pawl moving out of contact with the spring 40 but still in engagement with the tooth of the ratchet wheel and the holding pawl will drop into the next tooth to that with which it was previously engaged. Thus the load can be lowered one tooth at a time by moving the handle 20 back and forth.

As previously noted, it is frequently desired to lower the load faster and still maintain control thereof. This effected by moving the cam lever 460 to cause the holding pawl to be moved laterally outward toward the frame compressing the spring 38 which brings the tooth engaging end of the holding pawl over the disc 16d. It is still over the ratchet wheel also. As previously described the tooth engaging end of the pawl could be in engagement with one of the ratchet wheel teeth and be blocked from lateral movement by the disc, but will snap over into position when a coinciding notch and tooth come opposite to the pawl upon movement of the ratchet wheel.

Under this condition when the ratchet handle is brought down to the point where the ratchet pawl is pushed into engagement with the tooth next to the one being engaged by the holding pawl and the ratchet wheel moved to cause the release of the holding pawl, the holding pawl cannot drop into the next succeeding ratchet wheel tooth because the disc 16d holds it away from the ratchet wheel until the next succeeding ratchet tooth and notch come under the pawl. Thus when the handle 20 is moved backward or clockwise the drum is rotated by the pull of the cable four teeth for each stroke of the handle or, under the arrangement shown, one quarter of a revolution which is nearly the full stroke of the ratchet handle and the load is lower by four teeth instead of one. Thus the load lowering speed is greatly increased.

In order to condition the device for normal raising of a load the cam lever 46 is merely moved back to the position where the cam surface 46b settles into the notch 40b and the spring 38 returns the holding pawl 36 to its normal position opposite the ratchet wheel and out of possible engagement with the disc 16e.

I claim:

1. A hoist of the class described wherein a flexible load engaging member is secured to a spool disposed in a frame and the spool has end flanges with ratchet teeth on at least one of the flanges to form a ratchet wheel and ratchet means for turning the spool includes a pivoted handle and a ratchet pawl carried by the handle for engagement with the teeth on the ratchet wheel and a holding pawl is carried by the frame and operates in conjunction with the ratchet pawl and ratchet wheel to control the movement of the spool for raising and lowering a load, the improvement in means for rapidly lowering a load which comprises holding pawl disengaging means extending alongside the ratchet wheel for holding the pawl from engagement with the ratchet wheel for a lesser number of teeth then are on the ratchet wheel and means for holding said pawl for lateral movement in said frame and means for moving said holding pawl laterally in said frame into operative engagement with the holding pawl disengaging means;

the means for moving the holding pawl laterally on the shaft comprises a cam means rotatably disposed on the shaft and said holding pawl has a cam engaging surface and said cam means is disposed in engagement with said cam engaging surface; I said holding pawl is provided with a hub and said cam surface is formed on the end of the hub;

said cam means includes a lever carried on a hub and said cam is formed on the end of the hub toward the holding pawl means: a shaft is disposed in the frame and the holding pawl is rotatably disposed on the shaft and a first spring means is disposed around the shaft and has one end connected to the holding pawl and the other end fixedly held for urging the holding pawl into engagement with the ratchet wheel, a second spring is disposed around the shaft and has one end connected to the holding pawl and the other end disposed in the path of the ratchet pawl to rotate the holding pawl out of engagement with the ratchet gear;

a third spring is disposed around the shaft between the cam lever hub and the frame to hold the cam in engagement with the cam engaging surface.

2. An apparatus as described in claim 1 wherein first spring means is of open convolution and said third spring means has greater resistance to compression

Claims

1. A hoist of the class described wherein a flexible load engaging member is secured to a spool disposed in a frame and the spool has end flanges with ratchet teeth on at least one of the flanges to form a ratchet wheel and ratchet means for turning the spool includes a pivoted handle and a ratchet pawl carried by the handle for engagement with the teeth on the ratchet wheel and a holding pawl is carried by the frame and operates in conjunction with the ratchet pawl and ratchet wheel to control the movement of the spool for raising and lowering a load, the improvement in means for rapidly lowering a load which comprises holding pawl disengaging means extending alongside the ratchet wheel for holding the pawl from engagement with the ratchet wheel for a lesser number of teeth then are on the ratchet wheel and means for holding said pawl for lateral movement in said frame and means for moving said holding pawl laterally in said frame into operative engagement with the holding pawl disengaging means; the means for moving the holding pawl laterally on the shaft comprises a cam means rotatably disposed on the shaft and said holding pawl has a cam engaging surface and said cam means is disposed in engagement with said cam engaging surface; said holding pawl is provided with a hub and said cam surface is formed on the end of the hub; said cam means includes a lever carried on a hub and said cam is formed on the end of the hub toward the holding pawl means: a shaft is disposed in the frame and the holding pawl is rotatably disposed on the shaft and a first spring means is disposed around the shaft and has one end connected to the holding pawl and the other end fixedly held for urging the holding pawl into engagement with the ratchet wheel, a second spring is disposed around the shaft and has one end connected to the holding pawl and the other end disposed in the path of the ratchet pawl to rotate the holding pawl out of engagement with the ratchet gear; a third spring is disposed around the shaft between the cam lever hub and the frame to hold the cam in engagement with the cam engaging surface.

2. An apparatus as described in claim 1 wherein first spring means is of open convolution and said third spring means has greater resistance to compression than the first spring means.