US 3566386 A
Description (OCR text may contain errors)
Feb 23, 1971 M, w. HAMILTON CRANE ANGLE INDICATING SYSTEM Filed Feb. 6, 1968 3 Sheets-Sheet l A ff# /4/ Feb.\23, l1971 M. w. HAMIL'roN 3,565,336
y CRANE ANGLE INDICATING SYSTEM Filed Feb. 6, 1968 3 Sheets-Sheet 2 yww l! l l 4 ATTORNEYS Feb- 23, 1971 M. w. HAMILTON 3,565,336
CRANE ANGLE INDICTING' SYSTEM n l 3 Sheets-Sheet 5 Filed Feb. 6. 1968 INVENTOR.
United States Patent O 3,566,386 CRANE ANGLE INDICATING SYSTEM Martin W. Hamilton, Mount Prospect, Ill., assignor to Eaton Yale & Towne Inc., a corporation of Ohio Filed Feb. 6, 1968, Ser. No. 703,444 Int. Cl. G0811 21/00 U.S. Cl. 340-267 9 Claims ABSTRACT F THE DISCLOSURE A monitoring and alarm system for a tower crane which warns the operator of the crane if predetermined angular limits are exceeded. Tower cranes must be operated within certain limits as determined by the position of the crane boom and if such limits are exceeded, a dangerous condition exists. The present invention warns if the crane angle reaches a dangerous condition.
BACKGROUND OF THE INVENTION Field of the invention The invention relates to monitoring and warning devices for a tower crane so as to indicate if a dangerous condition is being approached by the crane angle.
DESCRIPTION OF THE PRIOR ART Tower cranes have been used and it has been customary for an operator to observe charts and the angle of the boom and estimate from within the crane cab whether a dangerous condition exists.
SUMMARY OF THE INVENTION The present invention relates to a warning and monitoring device which produces an audible and visual indication if the crane angle of a tower crane approaches or exceeds a preset limit. This allows the operator to set the warning device to the predetermined boom angle depending on load and other factors and then concentrate on moving the loads with the crane. He does not have to continuously observe the crane angle and estimate when a dangerous condition is being approached since he knows that the warning and monitoring device of this invention will automatically give him an audible and -visual indication when a limiting crane angle is being approached or exceeded.
Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which preferred structural embodiments incorporating the principles of the present invention are shown by way of illustrative example.
BRIEF DESCRIPTION OF TH DRAWINGS FIG. 1 illustrates a tower crane in which the present invention is used;
FIG. 2 isa front view of the warning and monitoring indicator;
FIG. 3 is a top view of the indicator; and
FIGS. 4A and 4B are schematic diagrams illustrating the control and wiring portion of the warning and monitoring device.
DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates a crane 10' mounted on a truck 15 and which carries a first boom portion 11 which extends upwardly from the crane cab 10. A second boom portion 12 is pivotally attached to members 16 and 17 of the first boom portion 11 by pivot pins 13 and 14 and extends generally horizontally. An end portion 18 of the boom portion 12 carries a pulley. A cable 21 has one end ICC connected to the end portion 18 and passes down over a pulley which supports a hook 19. The cable passes over a pulley 24 to a winch 25 mounted within the cab 10. Suitable driving and control means are connected to the winch 25 to allow the hook 19 to be moved upwardly and downwardly relative to the boom portion 12. A second winch 22 is connected to a cable 23 which passes over support members 30 and 25 to the end 18 of a boom portion 12. Winch 22 and cable 23 control the angular position of boom portion 12 relative to the boom portion 11. Since the boom portion 12 is pivotally attached to the portion 11 it may be pivoted upwardly and downwardly from the horizontal.
The present invention provides an audible and visible alarm to indicate to the operator of the crane when the boom portion 12. reaches a predetermined limiting angle so as to give him warning both visually and audibly so that he will be aware of the condition and correct it.
The warning and monitoring device is illustrated in FIGS. 2 and 3. FIG. 2 illustrates a meter 26 with an indicator 37 that may be read against an indicia 38 printed on the face of the meter. A power-on switch 27 supplies power to the device and the meter has a separate switch 28. The visual alarm 29 is mounted on the face of the meter 26 and lights up to indicate to the operator when the preset angle of the boom has been exceeded. An audible warning horn 34 is also mounted on the meter 26 and audibly indicates that the angle to which the warning device has been set has been exceeded.
A warning angle setting knob 31 is mounted on the top of the meter 26 and has a pointer 33 that may be read against suitable indicia 45. A lock 32 is rotatably mounted on meter 26 and allows the warning knob 31 and pointer 33 to be locked in any preset position. By loosening the lock 32 the pointer and knob 31 may be rotated to a different setting and locked in that position by retightening the lock 32.
FIGS. 4A and 4B illustrate the electrical schematic of the warning and monitoring device. As shown in FIG. 4B the angle transducer 41 comprises a 90 precision potentiometer with a weighted pendulum 42 attached to it. The transducer 41 produces an output signal proportional to the angle of rotation from a horizontal reference. The pendulum may be damped to prevent excessive mechanical oscillation as for example by utilizing a permanent magnet field which causes eddy current drag in the pendulum proportional to the rate of oscillation. The transducer 41 is mounted on boom portion 12.
The pendulum controls the position of a wiper contact 43 which engages the potentiometer R1. Wiper contact 43 is connected to terminal 46. One end of resistor R1 is connected to terminal 44 and the other end is connected to terminal 47. A grounded terminal 48 is in the transducer 41 also. Contact 44 is conneced through terminal block 49 to a resistor R6 which has its other side connected to a terminal J on a terminal block 60. Contact 46 is connected to terminal K of terminal block 60. Contact 47 is connected through terminal block 49 to terminal D of terminal block 60 and to one side of meter 26. A full wave rectifier comprises diodes D2, D3, D4 and D5 and produces a rectied output on terminals 61 and 62. Input terminals 63 and 64 are connected to a suitable direct current supply for example between 12 and 30 volts DC.
One of the leads 63 is connected to a positive terminal of the voltage supply and the other 64 is connected to the negative supply. A condenser C4 is connected across terminals 61 and 62 to lter out noise from the generator. The rectifier 65 takes care of positive or negative ground on the machine such that terminal 61 is connected to the positive terminal and 62 to the negative terminal. A switch 27 which is the power-on switch is connected to lead 61 and to a fuse 66. Lead 67 is connected from fuse 66 to terminal H on terminal board 60. Terminal A of terminal board 60 is connected to ground and to lead 62. A horn 34` and transistor T12 are connected in series between leads 62 and 67. A diode D5 has one terminal connected to the junction point between horn 34 and transistor T12 and its other side connected to the warning light 29. The other side of light 29 is connected to an electrode of a transistor T13. Another electrode of transistor T13 is connected to lead 67. The base of transistor T13 is connected to contact F on terminal board 60. A resistor R2 is connected to the base of transistor T12 and the other side of the resistor is connected to terminal C of terminal board 60. Terminal J of terminal board 60 is connected to lead 68. Resistors R3 and R5 have one side connected to lead 68, and their other ends connected together and to the emitter of transistor T12. A potentiometer R1 has a first wiper contact 73 which is connected to terminal B on terminal board 60. Wiper contacts 71 and 72 are electrically connected to opposite ends of resistor R4 and engage respectively resistors R3 and R5. Terminal hoard 60 is illustrated in FIG. `4A. Terminal A is connected to ground and contact B is connected by lead 76 to the base of a transistor R0. Contact C is connected to the emitter of a transistor T11. Contact D is connected to the base of a transistor T0. Contact F is connected to the emitter of a transistor T1. Contact H is connected to the junction points between resistors R23 and R29 and to one side of resistor R30. The other side of resistor R23 is connected to the base of transistor T1. The other side of resistor R29 is connected to the emitter of transistor T1, and the other side of resistor R30 is connected to the emitter of transistor T1.
Contact J is connected to the emitter of transistor T1. Contact K is connected to the base of a transistor T2 and contact L is connected to a resistor R19. The other side of resistor R19 is connected to a wiper contact 77 which engages a resistor R13.
A resistor R1 is connected between the emitters of transistors T1 and T2 and the resistor R3 has one side connected to ground and the other side connected to a wiper contact 718 which engages resistor R1. The collector of transistor T1 is connected to a suitable B+ voltage. The base of transistor T1 is connected to one side of a resistor R12 which has its other side connected to the base of transistor T9 and to the emitter of a transistor T4. The emitter of transistor T3 is connected to B+ and the base of transistor T3 is connected to the collector of transistor T2. A capacitor C1 and resistance R11 are connected in series between the hase and collector of transistor T3. The base of transistor T4 is connected to the collector of transistor T3. The base of transistor T4 is also connected to one side of a resistor R10 that has its 0pposite side connected to ground. The collector of transistor T1 is connected to B+ and its emitter is connected to a resistor R11 which has its opposite side connected to ground. The base of transistor T9 is connected to the emitter of transistor T4. Resistors R20, R21 and R22 are connected in series between B+ and ground. A condenser C3 is connected between B+ and the base of transistor T5. A wiper contact 79 is connected to the base of transistor T and engages the resistor R21. The emitters of transistors T5 and T0 are connected together and to one side of a resistor R25 which has its other side connected to ground. The condenser C5 is connected between ground and the collector of transistor T6. A center diode D1 is connected between ground and the base of transistor T5. A resistor R21 is connected between the base of transistor T5 and B+. Collector of transistor T5 is connected to the base of transistor T1. Transistor T has its emitter connected to B+ and hase connected to the collector of transistor T9 and to a condenser C1. The other side of condenser C4 is connected to a resistor R23 which is connected to the collector of transistor T10. The collector o f transistor T10 is also connected to resistor R24 which has its other side grounded. Transistor T11 has its collector connected to B+ voltage and its emitter connected to a resistor R20 which has its other side grounded. Transistor T9 has its collector connected to B+ and its emitter connected to a potentiometer R13 which has its other side connected to the emitter of transistor T9. A wiper contact 81 engages the resistor R13 and is connected to one side of a resistor R15. The other side of resistor R15 is connected to ground. The base of transistor T9 is connected to one side of resistor R15 which has its other side connected to a B+ voltage. The collector of transistor T9 is connected to B+ through a resistor R14. The collector is also connected to the base of transistor T10.
yln operation, the crane operator unlocks the lock 32 and adjusts the knob 31 so that the pointer 33 reads against the indicia `45 to the desired limiting angle of the crane portion 12. Switches 27 and 28 are turned on to energize the warning alarm and angle indicator. In a particular embodiment B+ voltage was 11 volts and the B+ voltage was +6 volts. Wiper contact 72 is set by knob 31 to the desired warning angle. Transistor T13 is a regulator across the warning system. Transistor T12 drives the horn `34 and the light 29 when the set point is reached for a warning. The rectifier 65` solves the problem of positive or negative grounds and is a bridge rectifier so that the system operates properly whether particular machine and power system ground either the positive or negative side of the power supply. The condenser C1 filters out noise from the generator and other sources. Wiper contact 73 may be adjusted to adjust the zero setting of the needle 37. Transistors T5, T 0 and T1 cornprise a regulator control. Wiper contact 77 allows the angle calibration to be made and the transistors T1, T2, T3 and T4 comprise an operational amplifier and receive an input from contact K and L of the terminal block 60 which is indicative of the angle of the pendulum 42. Transistors T8, T9, T10 and T11 comprise a second operational amplifier which drives the alarm system. Tran1 sistors T8 and T9 comprise a differential amplifier and drive the alarm system. Note for example, that the emitter of transistor T11 is connetced to terminal C of terminal block 60 and that terminal block 60 has its Contact C connected to the resistor R2 which in turn is connected to the base of transistor T12 in FIG. 4B. When the differential amplifier comprising the transistors T8 and T9 is keyed, a bias supply is applied through contact C to the base of transistor T12 topturn on the horn 34 and the light 29. The bias point for the operation of the circuit can be adjusted by moving knob 31 which controls the wiper contact 72.
Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of my contribution to the art.
I claim as my invention:
1. A warning and monitoring device for a tower crane with a movable boom which has first a boom portion that is substantially vertical and a second boom portion pivotally attached to the second boom portion comprising:
an angle transducer vmounted on the second boom portion and producing an output proportional to the angle of the second boom portion relative to the horizontal and comprising a potentiometer with a ywiper contact and a pendulum pivotally supported yand attached to the Wiper contact,
an alarm set potentiometer Iwith a wiper contact that may be set to select a warning angle,
a flip-flop circuit comprising a first pair of transistors with one biased on and one biased ofi during safe operating conditions of said crane, said wiper contacts of said alarm set potentiometer connected to said normally on transistor and said wiper Contact of said angle transducer connected to said normally olf transistor, and an alarm device connected in circuit with said normally off transistor to produce a warning when the second boom portion has an angle which is beyond that set in the alarm set potentiometer. 2. A warning and monitoring device according to claim 1 comprising a set shaft connected to the wiper contact for varying the output of the alarm set circuit.
3. A warning and monitoring device according to claim 2 comprising a knob on the set shaft, and means for seiectively locking the shaft.
4. A warning and monitoring device according to claim 3 comprising indicia adjacent the knob to allow the alarm set circuit to be set to a selected output.
5. A warning and monitoring device according to claim` 1 wherein the alarm device produces a visual output.
6. A warning and monitoring device according to claim 5 wherein the alarm device is a light bulb.
7. A warning and monitoring device according to claim 1 wherein the alarm device produces an audible output.
8. A warning and monitoring device according to claim 7 wherein the alarm device is a horn.
9. A warning and monitoring device according to claim 1 including a meter for indicating the angle of the second boom portion.
References Cited UNITED STATES PATENTS ALVIN H. WARING, Primary Examiner D. L. TRAFTON, Assistant Examiner U.S. Cl. X.R.