US1396532A - Means for braking-cranes - Google Patents

Description

H. E. SCOTT.

MEANS FOR BRAKING CRANES.

APPLICATION FILED JUNE 12. 1920.

Patented Nov. 8, 1921.

3 SHEETS-SHEET 1.

ITNESS.

Haw f. Scofi. 5r

H. E. SCOTT.

MEANS FOR BRAKING CRANES.

APPLICATION FILED mm: 12, I920.

Patentd Nov. 8, 1921.

3 SHEETS-SHEET 2- INVENTOR WITNESS:

H. E. soon.

MEANS FOR BRAKING CRANES. APPLICATION FILED JUNE 12, 1920.

3 SHEETSSHEET 3.

RAD/us 'INVENTOR: m 5560.

UNITED STATES PATENT OFFICE.

HARRY E. SCOTT, OF CLEVELAND, OHIO, ASSIGNOBLTO THE BROWN HOISTING MACHINERY COMPANY, OF CLEVELAND, OHIO, A CORPORATION.

MEANS FOR BRAKING-CRANES.

Application filed June 12,

T all whom it may concern.

Be it known that I, HARRY E. Scorr, a citizen of the United States, residing in the city of Cleveland, county ofCuyahoga, and State of Ohio, have invented a new and useful Means for Braking-Cranes, of which the following is a full, clear, and exact-description, reference being made to the accompanying drawings, which form a part of the specification, and wherein similar parts are designated by the same numerals in each case.

My invention relates to and comprises generally, those forms of machines and mechanisms, like overhead cranes,-man-trolleys, rope system bridge tramways and boom cranes, wherein'loads are hoisted or lowered vertically by means of load-sustaining pulley systems and winding drums, and, with appropriate adaptations, it is directly applicable to any such.

In order to illustrate and point out a concrete mode of applying the invention, I have selected for the purpose that type of boom crane wherein, unlike the fixed boom type, the primary load that figures in the invention, is that due to the weight or pull of the boom itself.

In this latter type, the boom being vertically hinged, require a special pulley sys tem and drum to adjust the boom to its different radii, and the weight to be sustained thereby varies in consequence with the different vertical positions of the boom. This movability of the boom, however, much enlarges the usefulness of such cranes, as compared with cranes with fixed boom radii, in that, by merely moving the boom about its pivotal connection, a load may be picked up, or deposited in spite of intervening obstacles. or varying levels, and by booming the load." it is called. such change of levels may be brought about while the boom is being swung, or rotated. toward a given terminal point. This added utility. however, is not without a corresponding disadvantage. \Vhile both types of cranes are equally liable to overturn when they engage an excess load, thi liability in the case ofcranes with variable boom radii, increases according as the boom radius is increased, and, for this reason, a load that is safe when taken on. may becomeunsafe when lowered by the boom to a longer radius. 'Heretofore, in practice, whether or not a given load was Specification of Letters Patent.-

Patented Nov.l8, 1921.

1920. Serial No. 388,583.

within the designed capacity of the crane at any time, has been left entirely to the judgment of the operator, without aid from.

or restraint by the mechanism itself. In consequence many accidents have occurred of a character that it is highly desirable to avoid, or reduce.

It is the province of the present invention to so arrange and correlate the .parts and mechanisms in apparatus of the kind in question, and to make use of certain operative possibilities involved, as to provide a means of remedying the situation described, which may be simply and inexpensively applied.

In the drawings, Figure 1 is a side elevation of a locomotive crane embodying .the invention.

Fig. 2 is an enlarged plan view of the brake mechanism shown in Fig. 1.

Fig. 3 is a sectional view on the line m of Fig.1

Fig. 4 is a perspective line view of certain braking details pertinent.

Fig. 5 is a side view of certain boomhoisting, and boom-lowering control detail.

Fig. 6 is a sectional view, on lines 11 y, in Fig. 5.

Fig. 7 is a top View of the hoisting part. or element, the subject of Fig. 5, with the two lower pawls removed.

Fig. 8 is a line diagram toillustratethe proportional variations on the boom-sus taining rope, when the boom and its load are in different radial positions.

Figs. 9, 10 and 11 are similar diagrams to illustrate, that when the load is varied ac cording to the radial position and value of the boom, such strain or tension will remain constant.

The several figures show an ordinary locomotive crane having a four-part rope system for the boom, and a separate system for the load proper.

The boom 8 thereof is pivoted to the crane body, upon which a hoist-rope winding drum 6. provided witha rope 7 is mounted.

9 indicates the source of power, by which the shaft 10 is actuated through the connectingrod 11, andthe crank-disk 12. 13 is a spur-gear. onthe shaft 10, in mesh'with a similar gear 14, on a shaft 15, parallel to 10. On the end. of the shaft 15, is a spur pinion 16 meshing with a spur gear 17 on a brake shaftfll8,

The shaft 18 carries a spur pinion 19 which meshes into a drum gear 20, on a fixed drum shaft 21. The shaft 18 also carries a brake wheel 22,of a construction, and having such location relatively to other parts,

that will be further explained. The band 23 of said brake-wheel, is anchored to the drum shaft 21, and is provided, in the customary manner, with brake-band, rod 24, having its outer end pivotally connected to the brake-lever. 25. The lever 25 is transversely related to the frame of the crane superstructure, and is pivotally connected thereto, near the inner end of said lever, at 26. (See Fig. 3). Its outer end is engaged by a release cord, or rope, 27, which is led forwardly to a pulley, or drum-like anchor age 28, at or near the operators station in the cab. Saidanchorage is provided with a hand-lever 29, by Which'it may be rotated in order to wind in the rope 27 and actuate the lever 25, and thereby loosenand release the brake-band 23 and its braking-tension, whenevera prearranged resistance to such movement-as hereinafter expl.ained-does not exceed a predetermined amount. A lever sheave or wheel 30, is loosely mounted on the shaft 21; V I

The e-part rope system for operating the boom 8, comprises a sheave block 31, pivotally connected to the outer end of the boom, a sheave 32 on the crane frame, and the rope itself. Said rope is operatively attached, at one end, to the winding drum 5, and extends therefrom-as indicated by lto land around a sheave in the block 31., backwardly as indicated by 2-to and around the sheave 32, thence-as indicated.

by 3-to and around a second sheave in said block, and, thence,as indicated by Q-baclrwardly, to a purchase anchorage on the loose wheel 30. v a A A brake push rod 33, is hinged or otherwise connected, at one end, to thewheel 30, at a suitable point on thesame, to be pushed or withdrawn, according as said wheel, moved axially, in one direction or the other. The opposite end of said rod is pivotally joined to the brake lever 25, at a point 3% which is at a calculated distance from the fulcrum point 26, to insure that a given pull, or tension, of said rope, operating through said wheel, push-rod, brake-lever, and band,

will brake and hold said driving shaft 18, from rotation, and against any estimated. releasing counterforce that may beexerted upon the hand lever 29.

Figs. 5, 6, and 7, illustrate an adaptation of well known mechanical devices to meet the operative requirements of the brake wheel 22. As shown, the wheel proper 35 block is adapted to automatically engage the wheel 22, during the operation of lowering, and to be out of such engagement during the' operation of hoisting. The brake is always on and its hand in operative tension with said wheel while hoisting, but this e11- gagement does not interfere with the hoisting motion, since the pawls do not engage in this direction and the brake wheel remains stationary. During the operation of lowering, the pawls carry the brake wheel with them, and therefore lowering cannot take place until the band is released to a point where its resistance is less than the force driving the wheel in thelowering direction.

As will be understood, the only direct braking force involved in the apparatus now described, isthat exerted by the tension of the rope under varying conditions, and that the operator has no power to modify or control the braking process, except, indirectly and to the extent that he can exert force, through the hand-lever29, and the system of which it is a member, to overcome the force exerted, through the same system, by said tension.

In applying the invention therefore to cranes with movable booms, there should be taken into account the weight of the boom itself when at-its longestjradius, and the weight and downward pull of theload as suspended therefrom; obviously, the factor corresponding with the weight or downward pull of the vertically moving boom, when the device is applied to fixed boom cranes, or hoists without booms, will be the load that is specially grappled for hoisting or lowering on each' occasion; and with this, and tl'e estimated'muscular force to be exerted by theoperator, as factors, to calculate the said leverage system, sothat said tension shall tend to keep thebrake locked at every stage, and can only be released and-unlocked by the operator, when that tension is within, and does not exceed, the limits of safety in each case.

ltleversely, if at any time, either in engaging, or lowering a load, the tension or pull of the. rope equals the combined force required to set the brake, and resist any attempt to release the same by means of the hand-lever 29, any further operations in a direction that will increase such tension will be stopped. Inasmuch as the booms movements cancontinue only so long the operator is able to keep his releasing lever 29 drawn back, it follows that if the leverage system is so proportioned that said arresting tension is sure to occur before the danger limit is reached, the operator will be powerless, in the event of'inattention or ignorance, to continue to hold the brake open, and keep the machinery in motion beyond such limit.

with a. movable boom, except as and when so expressly claimed, I do not intend to limit the patent sought to that special boom, but, by more enlarged claims, wish to equally cover the idea when applied to other forms of hoisting and lowering apparatus, which accomplish the desired braking by utilizing the tension of the hoisting-rope by substantially the same mechanism as shown, irrespective of the general design and character of such forms, as compared with the embodiment referred to, or the fact that the tension, in such cases, is due to the weight of the boom alone, the loads from time to time hoisted, or to the joint influence of both.

Having described my said invention and shown and explained a concrete application of the same, what I claim and wish to pro tect by Letters Patent is as follows 2- l. The combination, in braking mechanisms, for hoisting machines. of a wind ing drum loosely mounted on its shaft, a load-sustaining pulley-system, mechanism for braking the drum against unwinding movement when said mechanism is operatively subjected to the tensile force of the load sustained by said system, and means or applying force in opposition to said ten- ..ile force, said system being connectible to the load to be sustained and having one end of it rope member fastened to the drum, and the other end fastened to said braking mechanism in suitable manner to operatively subject the same to said tensile force, substantially as shown and described.

In a hoisting and lowering machine. a means for controlling the descent of the load, comprising the combination of a compound pulley system, a winding drum to which one end of the rope member of said system is suitably attached to be wound in when the drum rotates in one direction, and to be paid out when the drum rotates in the opposite direction. means for arresting the rotation of the drum in said opposite direction when the pull or tensile force of the rope-member, under the weight of the load it sustains. is exerted thereupon. for the purpose, the other end of said rope member being ogeratively connected to said means, together with means for releasing said arresting li'tlOll and holding the drum free of the same. when said pull or tensile force does not exceed a predetermined amount substantially as shown and described.

3. A means for braking load-hoisting and lowering machines comprising the combination of a load-sustaining pulley-system. a winding drum, provided with gearing, loosely mounted on a fixed shaft, a driving shaft therefor, driving gear on said shaft in mesh with said gearing, a brake wheel loosely mounted on the driving shaft, means on said shaft for engaging said wheel when said shaft rotates in a direction to'lower the load, means for braking the wheel while in said engagement and actuated by the tensile force of said system, means for applying force in opposition to said tensile force so exerted, one end of the rope member of said system being fastened to said drum, and the other end fastened to said braking mechanism in suitable manner to operatively subject said means to said tensile force, substantially as shown and described.

I. In cranes having vertically moving booms, the combination, with a boom-sustaining pulley-rope system connected to the boom, of a looselymounted winding drum therefore, means for revolving said drum in a direction to wind in the rope member of said system, means for arresting the revolution of the drum in the opposite direction, when said means is actuated by the tensile force of said rope member, and means for resistin said arresting action and releasing said drum, one end of the rope member in said system being operatively connected to said last named means, and the other end, to said drum, substantially as shown and described.

In a crane having a vertically swinging boom, the combination of a pulley-system, a loosely mounted winding drum for said system, mechanism for rotating the drum in a direction to raise said boom and for holding the same against rotation in the opposite direction when tensile force is applied, said pulley-system comprising one or more pulleys, and a rope reaved therethrough h wing one end of the same operatively attached to said drum, and, the other end, to said mechanism, together with means for exerting a force in opposition to the application of said tensile force. as stated, substantially as shown and described.

6. In a crane having a vertically movable boom the combination of a pulley-system for raising and lowering the same connected thereto for the purpose, aloosely mounted winding drum for said system, mechanism for rotating said drum in a direction to raise said boom, and for holding said drum against rotation in the opposite direction under the tensile force of said system, said system comprising one or more pulleys and a rope reaved therethrough. having one end thereof operatively fastened to said mechanism, and. the other end, to said drum. together with means for resisting said holding action of said mechanism when force is applied to actuate said means for the purpose, substantially as shown and described.

HARRY E. SCOTT.

In presence of- F. P. SIPP, A. A. ABERNETHY.

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