US3854128A - Safety device for crane - Google Patents

Safety device for crane Download PDF

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Publication number
US3854128A
US3854128A US00312225A US31222572A US3854128A US 3854128 A US3854128 A US 3854128A US 00312225 A US00312225 A US 00312225A US 31222572 A US31222572 A US 31222572A US 3854128 A US3854128 A US 3854128A
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United States
Prior art keywords
signal
load
detecting means
electric
boom
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Expired - Lifetime
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US00312225A
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English (en)
Inventor
S Yamagishi
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Furukawa Co Ltd
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Unic Corp
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Assigned to FURUKAWA COMPANY LIMITED, A CO. OF JAPAN reassignment FURUKAWA COMPANY LIMITED, A CO. OF JAPAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: UNIC CORPORATION
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
    • B66C23/88—Safety gear
    • B66C23/90—Devices for indicating or limiting lifting moment
    • B66C23/905—Devices for indicating or limiting lifting moment electrical

Definitions

  • a safety device for a crane comprises apparatus for Dec. 29, 1971 Japan 46-173 detecting a Work length of the crane a device for termining a safety or rated load corresponding to the 52 us. c1.
  • 340/267 0, 212/39 R detected Work length an instrument for detecting a 51 Int. c1...: B66c 13/48, G08b 21/00 actually lifted and apparatus for mparing the [58]
  • the safety device employs elements which UNITED STATES PATENTS produce electric signals, corresponding to rated and 3,549,876 12/1970 Hamilton 340/267 C lifted loads, which are compared. 3,618,064 ll/l97l Hamilton 212/39 R 3,638,211 1/1972 Sanchez 340/267 c 10 Claims, 4 Drawing Figures WIIRK RADIUS DETECTING MEANS /RATE[I LUAI] DETERMINING MEANS DIFF. AMP1 t (RELAY & CONTACTS L I 2 3 W0 NEG. FEEDBACK AMP.
  • a safety device for a crane comprising boom length detecting means for detecting boom length as an electric signal, work radius detecting means for receiving said boom length signal and generating directly as an electric signal corresponding to work radius, a product of said boom length signal and a cosine signal which is obtained by converting a boom inclination angle into an electric signal, lifted load detecting means for detecting a lifted load as an electric signal, rated load determining means for converting said work radius electrical signal received therein to a signal indicating a rated load corresponding to said work radius, and comparator means for comparing said signal indicating said rated load with said signal indicating said lifted load to produce an output signal for stopping the crane operation or operating an alarm device when said lifted load is equal to or more than said rated load.
  • rated load is intended to mean a safety load corresponding to the length of a boomof a crane actually used and hence a work radius of the crane.
  • An object of the invention is to provide an improved safety device for a crane which is provided with a simplified circuit arrangement, and capable of automatically continuously checking for safe crane operation even if the length of the crane varies and preventing any false operation thereby improving the efficiency in the crane operation.
  • Another object of the invention is to provide a safety device for a crane capable of automatically continuously checking for safe crane operation by comparison of a load actually lifted with a rated load to meet the work radius obtained from a boom length and a boom inclination angle.
  • FIG. 1 is a block diagram showing the principle of the safety device according to the invention
  • FIG. 2 is a diagram showing one example of a rated load curve
  • FIG. 3 is a diagrammatical elevation of a truck crane employing the safety device according to the invention.
  • FIG. 4 is a circuit arrangement showing one embodiment of a rated load determining means employed in the invention.
  • FIG. 1 illustrates the principle of the device according to the invention
  • boom length detecting means 1 convertsa boom length (L) into an electric signal L for detecting the boom length
  • work radius detecting means 2 converts a boom inclination angle (6) into an electric signal c050 and extracts an electric signal L cosH as a product of the signal c059 and the signal L of the boom length produced in the boom length detecting means 1.
  • the signal L cos0 indicates a work radius R of a crane.
  • Lifted load detecting means 4 converts the load actually lifted into an electric signal W which is transmitted together with the rated load signal W to comparator means 5 which discriminates the positive or negative value of the difference W W In case the load signal W is equal to or more than the rated load signal W that is W -W E0, the comparator means 5 produces an output signal which operates alarm device or crane operation stopping means 6.
  • the comparator means 5 does not produce any output signal because the alarm device or crane operation stopping means 6 need not be operated.
  • a truck 7 is equipped with a swivel slide 8, pivotal points 9 for a boom, luffing cylinders 10, a load cell 11 for detecting a load, a cord reel 12, a potentiometer 13 for measuring the boom length, the main boom 14 and a hook l5.
  • the boom length detecting means 1 shown in FIG. 1 consists of the cord reel 12 adapted to extend and retract a cord according-to the boom length, the helical potentiometer 13 which converts the boom length to an electric resistance with the aid of the cord reel 12, and a negative feedback amplifier circuit (FIG. 1) which converts the electric resistance to an electric voltage signal.
  • the work radius detecting means 2 consists of a potentiometer (FIG.
  • the lifted load detecting means 4 comprises the conventional load cell 11 in which a real stress acting on a wire rope for lifting is converted into an electric signal which is applied to an amplifier (not shown) to obtain a signal of electric voltage W corresponding to the load.
  • the amplification factor within the range of the work radius from zero to R is zero because the load signal W is constant and equal to the rated load signal W and the amplification factors within the ranges from R; to R R to R and R to R are (W W )/(R R,), (W;,W )/(R;,R and (W,W;;)/(R R3), respectively.
  • the rated load W is determined as a function of the work radius R Lcos 6 by the use of the circuit as .generator is so constructed that when it receives as an input a voltage corresponding to R Lcos 6, it will generate an output voltage corresponding to the rated load W Voltages corresponding to the maximum rates load W, and work radii R R and R are (r,,/r )E and (r' /r )E, (r,/r )E and (r /r ),E respectively.
  • the lamp is lighted, an alarm buzzer is energized or the operation of the crane is stopped.
  • the comparator means does not produce any out put to make the alarm device operate or stop the operation of the crane.
  • the safety device can always continuously monitor any excessive load more than a rated load meeting a work radius of the crane over the wide ranges of the boom length, the boom inclination angle and the lifted load without using a complicated electronic circuit, so that a crane operator can be absorbed in the crane operation without consuming time to consider the safety of the crane. Therefore, the efficiency in crane operation can be considerably improved.
  • the problem of delayed judgement of the operator which is encountered in the prior art in any dangerous condition, can be solved and when an operator falsely operates a crane, it is automatically brought into an inoperative state so that any dangerous condition caused by the malfunction can be avoided.
  • the safety device according to the invention can be advantageously applied to any kind of cranes having fixed or adjustable length booms.
  • a safety device for a crane comprising boom length detecting means for detecting a boom length including means for generating a first electric signal corresponding to boom length, work radius detecting means for receiving said first signal and for generating directly a second electric signal corresponding to work radius, said second signal being a product of said first signal and a third cosine signal corresponding to a boom inclination angle, said cosine signal being generated in said work radius detecting means, lifted load detecting means for detecting a lifted load including means for generating a fourth electric signal corresponding to the lifted load, a rated load determining means including means for converting said second signal received therein to a fifth electric signal indicating a rated load corresponding to said work radius, said rated load determining means including a polygonal line function generator having an operational amplifier circuit and diode switches for changing amplification factors according to said second signal, and comparator means for comparing said fifth signal with said fourth signal to produce a sixth output signal providing information concerning safe crane operation when said lifted load is equal to or more than said rated
  • said boom length detecting means (1) comprises a cord reel (12) adapted to extend and retract a cord according to a boom length, a helical potentiometer (l3) responsive to the movement of said cord to convert the boom length to an electric resistance, and a negative feedback amplifier circuit connected to the electric resistance for providing an electric voltage signal comprising said first signal.
  • said work radius detecting means (2) comprises a potentiometer, the resistance winding of which is wound in a cosine manner and a slider interlocked with a main boom (14) wherein a turned angle of the slider is proportional to a boom inclination angle an output voltage signal (L) from said boom length detecting means (1) being applied to the ends of said resistance winding of said potentiometer for producing a signal (L c050), corresponding to a work radius, which is generated from the turning angle of the slider, said signal (L) comprising said first signal and said signal (L eos0) comprising said second signal.
  • said lifted load detecting means (4) comprises a load cell (11) in which a real stress acting on a wire rope for lifting is converted into an electric signal which is applied to an amplifier to obtain a signal of electric voltage (W corresponding to the lifted load, said voltage (W comprising said fourth signal.
  • said rated load determining means (3) comprises an operational amplifier circuit and diode switches for changing amplification factors'according to an input voltage (L 0050 R) comprising said second signal, said amplification factors being (W -W1)/(R R,), (W -W R 'R and (W W )/(R,-R corresponding to respective ranges of work radii, wherein R R are work radii and W W, are corresponding rate loads.
  • said comparator means (5) comprises a differential amplifier, to the respective input terminals of which the fourth signal (WL) and a rated load signal (W comprising said fifth signal are supplied to discriminate the positive or negative value-of the difference between the signals (W and (W and wherein when the lifted load is equal to or more than the rated load, said differential amplifier produces an output signal comprising said sixth signal to operate an alarm device (6).
  • said alarm device (6) comprises a relay adapted to be operated by said output signal from said differential amplifier to close its contacts so that the operation of the crane is stopped.
  • a safety device for a crane comprising boom length detecting means (1) including a cord reel (12) adapted to extend and retract a cord according to a boom length, a first helical potentiometer (l3) responsive to the movement of said cord to convert the boom length to an electric resistance, and a first negative feedback amplifier circuit, connected to the electric resistance, for providing a first electric output voltage signal (L), a work radius detecting means (2) including a second potentiometer, the resistance winding of which is wound in a cosine manner, and a slider interlocked with a main boom (14) wherein a turned angle of the slider is proportional to a boom inclination angle (6), the output voltage signal (L) from said boom length detecting means (1) being applied to the ends of said resistance winding of said second potentiometer for producing a second signal (L cosO), corresponding to work radius, which is generated from the turning angle of the slider, lifted load detecting means (4) including a load cell (11) in which a real stress acting on a wire rope for lifting is

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Jib Cranes (AREA)
US00312225A 1971-12-29 1972-12-04 Safety device for crane Expired - Lifetime US3854128A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP17372A JPS5413651B2 (US20080293856A1-20081127-C00150.png) 1971-12-29 1971-12-29

Publications (1)

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US3854128A true US3854128A (en) 1974-12-10

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Application Number Title Priority Date Filing Date
US00312225A Expired - Lifetime US3854128A (en) 1971-12-29 1972-12-04 Safety device for crane

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US (1) US3854128A (US20080293856A1-20081127-C00150.png)
JP (1) JPS5413651B2 (US20080293856A1-20081127-C00150.png)
AU (1) AU448029B2 (US20080293856A1-20081127-C00150.png)
DE (1) DE2263122C3 (US20080293856A1-20081127-C00150.png)
FR (1) FR2166087B1 (US20080293856A1-20081127-C00150.png)
GB (1) GB1362110A (US20080293856A1-20081127-C00150.png)
ZA (1) ZA728662B (US20080293856A1-20081127-C00150.png)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922789A (en) * 1974-12-11 1975-12-02 Koehring Co Boom length sensing system with two-block condition sensing
FR2309460A1 (fr) * 1975-04-29 1976-11-26 Bbf Group Inc Systeme de signalisation de surcharges pour des chariots elevateurs a fourches et appareils similaires
US4006347A (en) * 1975-02-04 1977-02-01 Kruger & Co. Kg System for a crane boom
US4054055A (en) * 1976-08-06 1977-10-18 Precilec Device for controlling the load of a lifting appliance
US4057792A (en) * 1970-01-21 1977-11-08 Ludwig Pietzsch Overload safety device for telescopic cranes
US4205308A (en) * 1977-11-21 1980-05-27 Fmc Corporation Programmable alarm system for marine loading arms
DE3203553A1 (de) * 1981-02-04 1982-10-28 Kabushiki Kaisha Toyoda Jidoshokki Seisakusho, Kariya, Aichi Verfahren und vorrichtung zur anzeige des ladezustandes fuer einen gabelstapler
US4402350A (en) * 1979-11-12 1983-09-06 Fmc Corporation System for the control of a marine loading arm
US4523686A (en) * 1982-07-28 1985-06-18 Fmc Corporation Anti-two block system
FR2599015A1 (fr) * 1986-04-24 1987-11-27 Mo N Proizv Dispositif de protection des mecanismes de levage contre les surcharges et le renversement.
US10494234B2 (en) 2015-06-24 2019-12-03 Palfinger Ag Crane controller

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50114765A (US20080293856A1-20081127-C00150.png) * 1974-02-22 1975-09-08
GB1500501A (en) * 1974-04-10 1978-02-08 Pye Ltd Crane load indicating arrangement
JPS51124258A (en) * 1975-04-23 1976-10-29 Hitachi Ltd Device for detecting overload
JPS5470233U (US20080293856A1-20081127-C00150.png) * 1977-10-28 1979-05-18
JPS54120162A (en) * 1978-03-09 1979-09-18 Nippon Telegr & Teleph Corp <Ntt> Safety system against overturning of crane
JPS5570487U (US20080293856A1-20081127-C00150.png) * 1978-11-08 1980-05-15
JPS55164293U (US20080293856A1-20081127-C00150.png) * 1980-05-02 1980-11-26
GB2219113A (en) * 1988-05-20 1989-11-29 Teledyne Ind Curve approximating circuits
FR2633268B3 (fr) * 1988-06-27 1991-05-31 Roux Ind Sa Systeme limiteur de couple ou de moment pour engins de levage
JPH0220336Y2 (US20080293856A1-20081127-C00150.png) * 1988-09-08 1990-06-04

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3549876A (en) * 1968-03-07 1970-12-22 Eaton Yale & Towne Crane operating radius indicator
US3618064A (en) * 1969-08-20 1971-11-02 Eaton Yale & Towne Crane computer
US3638211A (en) * 1969-10-08 1972-01-25 Litton Systems Inc Crane safety system
US3638212A (en) * 1968-10-16 1972-01-25 Pietzsch Ludwig Overload safety device for jib cranes
US3724679A (en) * 1971-02-19 1973-04-03 Clark Equipment Co Indicator or control for cranes

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3371224A (en) * 1965-07-16 1968-02-27 Astrodata Inc High accuracy electronic function generator
JPS4414272Y1 (US20080293856A1-20081127-C00150.png) * 1965-08-11 1969-06-17
GB993954A (en) * 1966-07-07 1965-06-02 Weighload Ltd Safe load indicators in jib cranes
US3534355A (en) * 1967-03-28 1970-10-13 Dole Valve Co Load warning device
US3505514A (en) * 1967-11-13 1970-04-07 Eaton Yale & Towne Load warning device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3549876A (en) * 1968-03-07 1970-12-22 Eaton Yale & Towne Crane operating radius indicator
US3638212A (en) * 1968-10-16 1972-01-25 Pietzsch Ludwig Overload safety device for jib cranes
US3618064A (en) * 1969-08-20 1971-11-02 Eaton Yale & Towne Crane computer
US3638211A (en) * 1969-10-08 1972-01-25 Litton Systems Inc Crane safety system
US3724679A (en) * 1971-02-19 1973-04-03 Clark Equipment Co Indicator or control for cranes

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4057792A (en) * 1970-01-21 1977-11-08 Ludwig Pietzsch Overload safety device for telescopic cranes
US3922789A (en) * 1974-12-11 1975-12-02 Koehring Co Boom length sensing system with two-block condition sensing
US4006347A (en) * 1975-02-04 1977-02-01 Kruger & Co. Kg System for a crane boom
FR2309460A1 (fr) * 1975-04-29 1976-11-26 Bbf Group Inc Systeme de signalisation de surcharges pour des chariots elevateurs a fourches et appareils similaires
US4054055A (en) * 1976-08-06 1977-10-18 Precilec Device for controlling the load of a lifting appliance
US4205308A (en) * 1977-11-21 1980-05-27 Fmc Corporation Programmable alarm system for marine loading arms
US4402350A (en) * 1979-11-12 1983-09-06 Fmc Corporation System for the control of a marine loading arm
DE3203553A1 (de) * 1981-02-04 1982-10-28 Kabushiki Kaisha Toyoda Jidoshokki Seisakusho, Kariya, Aichi Verfahren und vorrichtung zur anzeige des ladezustandes fuer einen gabelstapler
US4523686A (en) * 1982-07-28 1985-06-18 Fmc Corporation Anti-two block system
FR2599015A1 (fr) * 1986-04-24 1987-11-27 Mo N Proizv Dispositif de protection des mecanismes de levage contre les surcharges et le renversement.
US10494234B2 (en) 2015-06-24 2019-12-03 Palfinger Ag Crane controller

Also Published As

Publication number Publication date
GB1362110A (en) 1974-07-30
JPS4872840A (US20080293856A1-20081127-C00150.png) 1973-10-01
DE2263122C3 (de) 1980-02-14
DE2263122A1 (de) 1973-07-05
DE2263122B2 (de) 1979-06-13
FR2166087B1 (US20080293856A1-20081127-C00150.png) 1976-10-29
JPS5413651B2 (US20080293856A1-20081127-C00150.png) 1979-06-01
FR2166087A1 (US20080293856A1-20081127-C00150.png) 1973-08-10
ZA728662B (en) 1973-08-29
AU448029B2 (en) 1974-05-09
AU4977172A (en) 1974-05-09

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AS Assignment

Owner name: FURUKAWA COMPANY LIMITED, 6-1, 2-CHOME, MARUNOUCHI

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNIC CORPORATION;REEL/FRAME:004926/0937

Effective date: 19880616

Owner name: FURUKAWA COMPANY LIMITED, A CO. OF JAPAN,JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNIC CORPORATION;REEL/FRAME:004926/0937

Effective date: 19880616