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Publication numberUS2418576 A
Publication typeGrant
Publication dateApr 8, 1947
Filing dateJun 24, 1944
Priority dateJun 24, 1944
Publication numberUS 2418576 A, US 2418576A, US-A-2418576, US2418576 A, US2418576A
InventorsConrad Harold L
Original AssigneeHarold E Conrad, Myrtle L Conrad
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Signal system for cranes
US 2418576 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

April 8, 1947. CONRAD 2,418,576

SIGNAL SYSTEM FOR CRANES Filed June 24, 1944 3 Sheets-Sheet l April 8, 1947. L, CONRAD 2,418,576

SIGNAL SYSTEM FOR CRANES Filed June 24, 1944 3 Sheets-Sheet 2 5 #0504124. (an Q75 INVENTOR.

April 8, 1947. H CONRAD 2,418,576

SIGNAL SYSTEM FOR CRANES Filed June 24, 1944 3 Sheets-Sheet 3 W204 04, (away IN VEN TOR. Q

Patented Apr. 8, 1947 UNITED STATES PATENT OFFICE SEGNAL SYSTEM FOR CRANES Application June 24, 194.4, Serial No. 541,930

3 Claims.

This invention relates to signallin apparatus and it has particular reference to a system for electrically transposing into audible and visible signals the load radius of a crane boom and the weight hoisted thereby.

There are many types of signalling apparatus designed to warn a crane operator at a given load moment, among which there are devices employing the pendulum. principle of determining the angle of the boom and which utilize audible signals as a warning to the operator to either reduce the load or elevate the boom. The present invention seeks to improve upon these types of signalling apparatus by affording a crane operator a constant medium, disclosing to him the load Weight and boom angle at all times during operation of the crane.

The principal object of the invention therefore is as stated, and further, to provide electrically actuated means for not only warning the operator of a crane against overtaxing the same, but also to keep him constantly informed as to both the weight of the hoisted load, Whether or not uncalculated variations occur therein by reason of centrifugal force in swinging the boom, and the angle of the boom, all of which are important to safe handling of the crane to avoid the likelihood of overturning under extreme conditions.

Another object of the invention is to provide a signal panel consisting of parallel columns of lights, one column being indicative of the weight of a hoisted load while the other represents the load radius of the boom. A a load is hoisted, the lights in the weight column become illumihated successively upward while the lights in the load radius column are likewise illuminated and so long as the Weight remains within a safe margin, only the visible signal is operative. However, provision is made that when the lights in both columns are illuminated simultaneously, an audible signal sounded to indicate overload, enabling the crane operator to ease oii on his load or change th angle of the boom to a position of greater safety.

With the foregoing objects as paramount, the invention has further reference to certain fea tures of accomplishment which will become a parent as the description proceeds, taken in connection with the accompanying drawings wherein:

Figure l is a diagrammatic view of the electrical Wiring of the invention.

Figure 1A is a detail face view or the signal panel of the invention.

Figure 1B is a view of the boom angle indicator dial in diametrical cross-section.

Figure 2 is a detail view of the boom angle indicator circuit and the weight indicator circuit, omitting the audible signal circuit.

Figure 3 is a diagram specifically showing the bell and ringer circuits between the boom angle indicator and weight indicator with the signal lights added.

Figure 4 is a diagram of the bell and ringer circuits.

Figure 5 is a detail view of a. type of tensiometer suitable if or use with the invention.

Figure 6 is a detail view of a pendulum type boom angle indicator also suitable for use in connection with the present invention.

Figure '7 is a detail view of a constant ringing drop used in conjunction with the invention.

Figure 8 is a detail view fragmentarily showing the pendulum and frame of Figure 6, illustrating the dual contacts thereof, and

Figure 9 is a modified form of boom angl indicator.

Continuing with a more detailed description of the drawings, it may be first pointed out that the present invention refers chiefly to the electrical system by which a crane operator is kept continuouslyinformed concerning variations in the angle of the boom as well a variations in the weight of a hoisted load. In order to accomplish this, provision is made for mechanically predetermining the tension on the dead line of a crane which represents the weight of a load supported thereby as Well as provision for mechanically indicating the varying angle of the boom as it changes positions in operation. The results of these two separate components of the invention are transposed into electrical signals in a manner to be presently described which, under normal operating conditions consist of parallel columns of lights in a panel, the lights of one column being of one color, denoting weight and the differently colored lights in the companion column denoting boom angle. As a load is hoisted by the boom, the lights in the weight column are illuminated progressively upward until the actual weight of the load is disclosed on the'panel opposite the column of lights. This is true also of the lights in the opposite column. The arrangement is such, that the lights of the weight column will not surpass those of the boom angle column unless it is desired to pick up an overload. When this occurs, an audible signal circuit is closed and remains closed until manually reset,

Referring now to the mechanical means for predetermining the tension on the dead line, previously mentioned, reference is made to Figure 5 wherein numeral l8 denotes the load supporting or dead line of a crane. Attached to this line is an angular arm H which, by virtue of an eye or a bolt l2, produces a bend in the line, as shown. Resisting the force tending to straighten the line is a spring l3, surrounding a rod 14, the latter being connected to the line by means of a small sheave 5. The spring and rod are arranged in a frame l8, on which is mounted a dial l'i'. This same reference character will be used throughout the drawings to denote the weight indicator dial. The movements of the rod 14 are transmitted to a pointer, which, on the other figures, is identified by reference numeral [8.

The tensiometer described in the foregoing and illustrated in Figure 5 of the drawings is of well known design but it is understood that any other alternative design may be used in connection with the invention as may be suited to the purpose. This applies also to the mechanical component which denotes the angle of the boom.

The inclinometer or boom angle indicating means consists in one form of a plate 19, in Figure 6, from which a segment of substantially a quarter of a circle is removed. Along the arcuate edge of the opening thus formed is arranged two rows of parallel contacts, generally designated by numeral 20. It has been found that by providing two instead of one row of contacts, current leakage, which would otherwise cause constant illumination of the signal lights, is avoided. These contacts are insulated from plate [3 by a mounting 2! of insulating material and are further insulated from each other. An expedient method of forming these contacts is to first secure two parallel wires to the mounting 2! and h sever them at predetermined intervals by sawing. The resultant segments of wire then form the individual contacts 3| which are connected electrically to corresponding contacts 32 on the weight indicator dial IT. A pendulum 23a is pivoted at 291) to a corner of the plate 19 in such manner that when the boom (not shown), on which the plate is mounted, is operated, the pendulum, in remaining perpendicular to the earth, will be in a position to engage each of the contacts 3! successively. Actual engagement however is efiected through the rollers 230 which are insulated apart and which are separately connected to the light and bell circuits to be presently described. A connection is also made between the pivotal point 2% of the pendulum to the source of current, comparable to the manner in which the pointer of the angle indicator dials, illustrated in companion figures, is electrically wired to the source, which will now be described.

In each of the Figures 1 to 4 inclusive, the load radius indicator is shown as consisting of a dial 24, over which operates two pointers 25 and 25a, one below the other. It is obvious that this dial, which is known as a whole circle indicator, may be substituted for the angle indicator of Figure 6, but in the form shown it is similar in function to the angle indicator illustrated in Figure 9.

The pointers 25 and 25a are provided with brush contacts 26 and 23a respectively, insulated apart and separately connected, electrically to the light circuit and bell circuit, as will become apparent presently.

The pointers 25 and 25a are caused to move in relation to changes made in the angle of a boom by a weighted pendulum 21, suspended on a. fulcrum 28 and which carries a gear 29, meshing with a pinion 30, mounted on the pointer shaft. Obviously, when the indicator is mounted on a crane boom, the pendulum 21 will remain perpendicular to the earth regardless of the angle to which the boom is moved. As the relative positions of the gear and pinion change, the latter will rotate, causing the pointer 25 to travel over the contacts 3| of the dial 24.

The individual contacts 3| of one row are connected to corresponding contacts 32 on the face of the weight indicator dial IT. The companion row of contacts 3| are connected to correspond ing lights of the indicator panel 34 (see Fig. 1).

The row of contacts 32 on the weight indicator dial I! are individually connected to corresponding lights 33 on the panel 34.

Under actual operating conditions, figures indicative of the degree of angularity of the boom may be placed opposite appropriate lights on the panel 34 and figures representing weight in pounds may be inscribed opposite appropriate contacts 32 on the dial 17. However, for the sake of a better understanding of the relationship between the contacts and lights, the contacts bear numbers on the drawing corresponding to those opposite the lights. For example, contact No, l on the boom angle indicator dial 24 is related to No. 1 contact on the weight indicator dial H as well as to the No. 1 light on the panel 34.

In Figure 1, which illustrates diagrammatically the complete wiring arrangement of the inventor, it will be observed that the lower portion of the panel 34 serves as a junction box, in which the terminals 36 ar mounted and to which are connected in sequence the wires 31 from the weight indicator and from one row of contacts of the angle indicator. These terminals are connected in sequence to the lights 33 indicative of the boom angle through wires 38.

Opposite the terminals 36 is a companion row of terminals 39 to which are connected wires 40 extending through conduit 4| to the companion row of contacts 3| of the angle indicator dial 24.

In Figures 1, 3 and 4, the corresponding weight and boom angle indicating circuits are shown as closed through the corresponding light, bell 42 and constant ringer 43, which indicates that a load is being hoisted with the boom at an unsafe angle. The pointers 25 and 18 of the angle and weight indicators respectively being on corresponding contacts No. 1, current from battery A flows through wire a through No. 1 light on the left side of the panel illuminating the same, thence through wir I) which extends through conduit 4| to contact No. 1 on the angle indicator dial '24, thence through engaging contact 26a on pointer 25a, thence through Wire 0 back to battery A, thereby illuminating No. 1 light denoting boom position. Simultaneously, current flows from battery B through wire d, through No. 1 light on the right side of panel 34, illuminating the same, thence through wire e to wire 1, through wire g to the No. 1 contact on the weight indicator dial I1, thence through pointer l8, through wire it and back to battery B through wire 1'. At the same time, the bell circuit is closed through wire 7' which energizes the magnets 44 in the constant ringer 43 (Fig. '7), causing the armature 45 to be attracted to release the spring contact 46. Current is established through wire is to the bell 42, by engagement of spring contact 46 with the terminal 41 of wire 7c. The circuit is completed through wires Z and 1.

When the relay or constant ringer drop is in the position shown in Figure 1, contact points p3 and p4 are closed, completing the circuit and permitting current to flow momentarily from binding post C2-C3 to an insulated post 82, energizing solenoids 44, which, in turn, attract the armature 45. The hook h is released to cause points pi and p2 to make contact. The circult is broken between posts C2-C3 and C2 and between contact points p3 and p4. The closing of points pl and p2 causes current to flow between posts C2C3 and C2, ringing the bell 42. The solenoids operate only when the contacts on the scale of the boom arc synchronize.

It is obvious by reference to Figure '7 that the bell 42 will continue to ring until the plunger 48 is manually pushed upward to reset the armature 45 and spring contact 4%, Simultaneous with the closing of the bell circuit as described, a red warning light 49, as shown in Figures 1 and 4 is caused to burn and, like the bell 42, is rendered inoperative only by manually resetting the constant ringer 43, as described. Shown intermediate the lamp 49 and bell 42 in Figure 3 is a green all clear signal 49a which is energized during inoperative periods of the warning signal.

The foregoing description deals with but a selected one of the series of individual circuits which connect the several contacts on the dials l1 and 24 with the lights and bell circuit. It is at once apparent that whenever the two pointers l8 and 25 engage corresponding contacts on their respective dials, the results are identical with those described above to warn the operator to ease off on his load or to move the crane boom to a safer angle. However, so long as the hoisted load remains within a safe margin in relation to a particular boom position, the lights in the column denoting the weight hoisted remain below and never surpass those in the column denoting the angle of the crane boom. It is apparent therefore that the operator before whom the panel 34 is mounted is at all times apprised concerning the position of the boom and the weight of the load hoisted thereby and is not required to rely upon the fixed charts and load diagrams which cannot embrace all conditions likely to be encountered.

Manifestly, the construction as shown and described is capable of some modification and such modification as may be construed to fall within the scope and meaning of the appended claims is also considered to be within the spirit and intent of the invention.

What is claimed is:

1. A signal system for boom equipped hoisting apparatus, including a signal panel carrying parallel columns of lamps, two sets of arcuately arranged and relatively spaced contacts, each set having a pointer movable thereover, one of said sets of contacts being indicative of various angular positions of the boom of said hoisting ap- 6 paratus and whose pointer is gravity controlled, the other of said sets of contacts being indicative of the weight of a load hoisted by said boom, means connecting the contacts of one set to corresponding contacts of the companion set, means connecting the contacts of said angle indicating set of contacts to one of said columns of lamps, means connecting said weight indicating contacts to the companion column of lamps, a current supply circuit, an audible signal circuit and means rendered operative through the connecting means upon contact of corresponding contacts of said sets by their respective pointers to close said audible circuit.

2. A signal system for boom equipped hoisting apparatus, two sets of individual contacts, the contacts of one set being in circuit with corresponding contacts of the companion set, a column of lamps individual to each set of contacts, the contacts of one set being in circuit with corresponding lamps of one column, the contacts of the companion set being in circuit with corresponding contacts of the other set, a boom controlled pointer movable over the contacts of one set, a pointer movable over the contacts of the other set and controlled by variations in the weight of a load hoisted by said apparatus, a supply circuit, an audible circuit and means for closing said audible circuit through said contact circuits when the moment of the load reaches a maximum limit.

3. In a signal system for boom equipped cranes, a pair of sets of relatively spaced contacts in which the individual contacts of one set are in circuit with corresponding contacts of the other set, a lamp individual to and in circuit with the contacts of each of said sets and arranged in parallel columns on a panel, means responsive to changes in the angular position of the boom of said crane for closing the circuit between individual contacts of one set and their respective lamps, means responsive to variations in the weight of a load on said boom for closing the circuit between individual contacts of the other set and their respective lamps, a supply circuit, an audible signal circuit and means energizing said signal circuit through said contact circuits when the boom angle and weight responsive means engage corresponding contacts of said sets of contacts.


REFERENCES CITED The following reierences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 716,263 Mott Dec. 16, 1902 942,964 Jurnick Dec. 14, 1909 1,040,586 Selden et a1 Oct. 8, 1912 2,015,957 Neal et al. Oct. 1, 1935 2,022,844 Christian Dec. 3, 1935 2,346,066 Conrad Apr. 4, 1944

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US716263 *Feb 11, 1902Dec 16, 1902Laurence MottSpeed-indicator.
US942964 *Aug 16, 1907Dec 14, 1909Electric Bank Prot CompanyElectric-lighting attachment for burglar-alarm systems.
US1040586 *Feb 28, 1911Oct 8, 1912Metellus D SeldenAutomatic electric speed-regulator.
US2015957 *Dec 23, 1930Oct 1, 1935J O NealSafety device for the prevention of overloading cranes and the like
US2022844 *Nov 3, 1934Dec 3, 1935Christian Herbert AIndicator
US2346066 *Oct 12, 1942Apr 4, 1944Conrad Joshua COverload and radius indicator for cranes
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2772411 *Oct 25, 1954Nov 27, 1956Fishfader SBoom angle indicator for cranes
US3124206 *Feb 15, 1962Mar 10, 1964 Weighing systems
US3228019 *Sep 30, 1963Jan 4, 1966Mark Visceglia IncAdjustable boom angle warning device
US3362022 *Apr 22, 1965Jan 2, 1968Bucyrus Erie CoSafe load warning system
US3505514 *Nov 13, 1967Apr 7, 1970Eaton Yale & TowneLoad warning device
US3859651 *Jan 14, 1974Jan 7, 1975Thomas Jr Thomas WBoom angle indicator
US3965464 *Nov 21, 1974Jun 22, 1976Morita Pump Kabushiki KaishaDevice for automatically detecting overload on aerial ladder truck
US7325327 *Sep 12, 2003Feb 5, 2008Fischer David CMethod and apparatus for measuring angular or linear displacement
US20040080306 *Sep 12, 2003Apr 29, 2004Fischer David C.Method and apparatus for measuring angular or linear displacement
U.S. Classification340/685, 177/46
International ClassificationB66C23/00, B66C23/90
Cooperative ClassificationB66C23/905
European ClassificationB66C23/90B