US3922605A

US3922605A - Electrical winch drum rotation indicating system

Info

Publication number: US3922605A
Application number: US531737A
Authority: US
Inventors: Ivan D Sarrell
Original assignee: Koehring Co
Current assignee: Bank of New England NA
Priority date: 1974-12-11
Filing date: 1974-12-11
Publication date: 1975-11-25
Anticipated expiration: 1992-11-25

Abstract

The disclosure relates to an electrical winch drum rotation indicator for providing a crane operator with an indication of winch drum rotation so that the winch may be properly operated when the load is out of the operator''s sight. A signal generating means on the winch drum generates two series of electrical pulses each related in frequency to the speed of rotation of the winch drum and having a phase relationship related to the direction of rotation of the winch drum. The two series of pulses control the operation of a bidirectional stepper motor mounted at the operator''s station so as to drive an output drive shaft of the motor at a speed related to the frequency of the two series of pulses. A tactile indicator is connected to be driven by the output drive shaft of the stepper motor and is conveniently provided at the operator''s station so as to provide the operator with a tactile indication of the speed and the direction of rotation of the winch drum. At least one of the two series of pulses may be utilized to drive an audio transducer such as a speaker to provide an audible indication of winch drum rotation in addition to the tactile indication.

Description

United States Patent Sarrell NOV. 25, 1975 i 1 ELECTRICAL WINCH DRUM ROTATION INDICATING SYSTEM [57] ABSTRACT The disclosure relates to an electrical winch drum rotation indicator for providing a crane operator with an iSOLATlON AMP VISUAL SPEED INDICATOR [75} Inventor: Ivan D. Sarrell, Rising Fawn, Ga.

I indication of winch drum rotation so that the winch [73] Asslgnee' wis (jompany Milwaukee may be properly operated when the load is out of the 1 operator's sight. A signal generating means on the [22] Filed: Dec. 11, 1974 winch drum generates two series of electrical pulses each related in frequency to the speed of rotation of [21] Appl' 53l737 the winch drum and having a phase relationship re lated to the direction of rotation of the winch drum. [52] U.S. Cl. 324/166; 116/1 l4 G; ll6/l l6 The two series of pulses control the operation of a bi- [5ll Int. Cl. .i G01? 3/48 directional stepper motor mounted at the operator's [58] Field of Search 73/488, 493, S10; station so as to drive an output drive shaft of the ll6/l l4 G. [[6, DIG. l7; 324/166. 168, 171 motor at a speed related to the frequency of the two series of pulses, A tactile indicator is connected to be [56] References Cited driven by the output drive shaft of the stepper motor UNITED STATES PATENTS and is conveniently provided at the operators station 2 473 542 6,1949 Philpmt 124/168 so as to provide the operator with a tactile indication 5 6 H957 Sparks G X of the speed and the direction of rotation of the winch 036,460 5H962 white et a1 324/168 X drum At least one of the two series of pulses may be 3110 35 10 19 5 Stevens H 2 7 utilized to drive an audio transducer such as a speaker to provide an audible indication of winch drum rota- Primary E am[ 1 r Jam5 tion in addition [0 the tactile indication. A i

ttorney, Agent, or Firm Andrew J Beck 12 Claims, 5 Drawing Figures I +|2VOC i l /sa us ll Q5 I26 FSTEPPER MOTOR g? i K1) 1: i lZO I SW1 I I244: l I28;

I12 l I "B i I \T\\\\44 I I l 50' O m I 102 n4 Jl 1 My L l 5 NO. SW1 i 4 I NC C I I +r2v0c l t r v 5/0 H 1 I PUDIOTRANSDUCER 1 I I I l I not C i g NO SW2 I l L J l l l I l U.S. Patent Nov. 25, 1975 Sheet 1013 3,922,605

U.S. Patent Nov. 25, 1975 Sheet 3 of3 3,922,605

TIII II I 20:33

w ww bm I I I I l I I I I J ELECTRICAL WINCH DRUM ROTATION INDICATING SYSTEM BACKGROUND OF THE INVENTION The present invention relates to winch operated hoist cable cranes and, more particularly, to a winch drum movement indicator system for providing a crane operator with an indication of rotation of the hoist cable winch drum.

A crane operator must often raise and lower loads at the end of a hoist cable with the load hidden from the operators view. Under such conditions, the operator ordinarily receives signals from someone who is positioned in visual communication with the load at all times. The operator typically receives instructions from that person through hand signals and, since it is virtually impossible to visually determine whether the hoist cable is paying out or running in, the operator must have some indication of hoist cable movement to properly follow the hand signals. Moreover, since movement of the load through very short distances on the order of one to two inches may be required, the operator must be provided with an accurate indication of hoist cable movement.

Since the hoist cable is typically wound on a winch drum and the load is raised and lowered by rotation of the winch drum, in one known system a sheathed cable such as the type used in automobile speedometers runs between the winch drum and the operator's station in the cab of the crane. The cable is connected to a rotary member which rides on the hub of the winch drum and is driven in response to rotation of the winch drum. Rotation of the rotary member is transmitted through the cable to the operators station. A small knurled knob is connected to the end of the cable and the operator can place a finger on the knob to receive a tactile indication of winch drum rotation.

Mechanical drum rotation indicator systems such as that described above are relatively expensive and inaccurate. Because of the distance between the cab of the crane and the winch drum, a very long cable is required to transmit winch drum motion to the operator's station in the cab. The cable length results in lost motion and thus inaccurate correlation between the rotation of the winch drum and the tactile indicator, particularly when the winch drum reverses direction. In addition, the transmission cable is often sheared when the operator, attempting to put useful pressure on the tactile indicator, uses excessive pressure and over torques the transmission cable.

SUMMARY AND OBJECTS OF THE INVENTION It is accordingly an object of the present invention to provide a novel winch drum movement indicator system which obviates these and other difficulties of the prior art.

It is another object of the present invention to provide a novel winch drum rotation indicator system which provides a tactile indication of winch drum rotation without danger of damage to the system from the application of excessive pressure to the tactile indicator.

It is yet another object of the present invention to provide a novel winch drum rotation indicator system wherein winch drum rotation is transmitted to the operator's station by relatively inexpensive electrical means It is a further object of the present invention to provide a novel winch drum rotation indicator system which provides both tactile and audible indications of winch drum rotation at an operators station remote from the winch drum.

These and other objects and advantages of the present invention are accomplished through the provision of a signal generating means which generates two series of electrical pulses each related in frequency to the speed of rotation of the winch drum and having a phase relationship related to the direction of rotation of the winch drum. The two series of pulses control the operation of a bidirectional stepper motor mounted at the operator's station so as to drive an output drive shaft of the motor at a speed related to the frequency of the two series of pulses and in a direction related to the phase relationship between the two series of pulses. A tactile indicator is connected to be driven by the output drive shaft of the stepper motor and is conveniently provided at the operator's station so as to provide the operator with a tactile indication of the speed and the direction of rotation of the winch drum. At least one of the two series of pulses may be utilized to drive an audio transducer such as a speaker to provide an audible indication of winch drum rotation in addition to the tactile indication.

The manner in which the present invention accomplishes these and other objects of the present invention and provides further advantages will become apparent to one skilled in the art to which the invention pertains from the following detailed description when read in conjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in elevation of a portion of a crane schematically illustrating one embodiment of a winch drum rotation indicator system constructed in accordance with the present invention;

FIG. 2A is a side view of one embodiment of the drum rotation detector of FIG. 1;

FIG. 2B is a view in elevation and partial cross section of the drum rotation detector of FIG. 2A;

FIG. 2C is a diagram graphically illustrating the waveforms produced by the detector of FIGS. 2A and 2B; and,

FIG. 3 is a circuit diagram schematically illustrating the system of FIG. 1.

DETAILED DESCRIPTION General System Description Referring now to FIG. 1 in which a section of a crane is illustrated in elevation, the crane may include a main winch 10 and an auxiliary winch 11 having winch drums I2 and I4 suitably driven about respective horizontally disposed axes I5 and 16. Load or hoist cables are wound on the winch drums l2 and I4 in a suitable conventional manner and extend along a boom (not shown) to a block or other load connecting means.

In accordance with the present invention, winch drum rotation detectors I8 and 20 are mounted adjacent the main winch l0 and the auxiliary winch 11, respectively, to generate electrical signals related to the speed and direction of rotation of the winch drums I2 and 14. In the illustrated embodiment, the detectors I8 and 20 are identical and each includes a roller or wheel 22 journaled for rotation on a shaft 24 connected to a cam and switching arrangement within the detector as- 3 sembly as is hereinafter described in greater detail. Each of the detectors l8 and 20 may be suitably mounted on an arm 26 which is pivotally mounted on the frame of the crane as is generally indicated at 28.

A spring 30 connected between the arm 26 and the frame of the machine biases the roller 22 of each detector assembly into contact with an inner rim 32 of the associated winch drum so as to insure good frictional contact therebetween. Accordingly, as the winch drums l2 and 14 rotate, the roller 22 is rotated at a speed and in a direction related to the speed and direction of rotation of the winch drum. Rotation of the roller 22 is translated into series of electrical pulses by the cam and switching arrangement of the detectors as will hereinafter be described.

The output signals from the detectors l8 and 20 may be transmitted by way of

cables

34 and 36, respectively, to a display and control panel 38 at an operators station in the cab 40 of the crane. As will hereinafter be described in greater detail, the signals from the detectors l8 and 20 may be utilized through the provision of appropriate circuitry within the display and control panel 38 to provide audible, visual and tactile indications of winch drum rotation. In this connection, it should be noted that separate circuitry may be provided for each winch drum or a suitable switching arrangement may be provided in the display and control panel 38 to permit the operator to select one of the two detector output signals for monitoring at any instant. Since the monitoring circuitry may be the same for each winch drum rotation indicator, only that employed in connection with the main winch will be described hereinafter.

To provide the tactile indication, a stepper motor may be mounted in the winch drum control handle 42 and may be connected to drive a tactile indicator 44 such as a knurled knob protruding from the handle 42 in a position convenient to the operator's touch. The stepper motor in the handle 42 may be driven in response to the signals from the detectors [8 and 20 and may be connected to the control and indicator panel 38 by way of electrical conductors 46 to receive appropriate drive signals.

The signals related to winch drum rotation provided by the detectors 18 and 20 are preferably pulses which provide information as to the speed and direction of rotation of the winch drums l and 11. In accordance with the preferred embodiment of the invention, the stepper motor which drives the tactile indicator 44 of FIG. I is preferably driven by at least two series of pulses. The frequency of the two series of pulses determines the speed of rotation of the stepper motor and the phase relationship between the two series of pulses determines the direction of rotation of the stepper motor. Accordingly, the detectors l8 and 20 preferably generate at least two series of pulses which have a frequency related to the speed of rotation of the winch drums and which have a phase relationship indicative of the direction of rotation of the winch drums.

Drum Rotation Detector One embodiment of a suitable detector for providing the desired two series of pulses is illustrated in FIGS. 2A and 2B. While the illustrated embodiment is electro-mechanical, i.e. a cam and switching arrangement, it should be understood that other means such as photoelectric cells or magnetic pickups may be employed to generate the rotation responsive pulse signal.

Referring now to FIG. 2A, the roller of wheel 22 which rides in frictional engagement with the inner rim 32 of the winch drum is connected to the shaft 24 as was previously described. The shaft 24 passes through the pivoted arm 26 and into a detector housing 50 and is journaled for rotation therein. As is shown more clearly in FIG. 28, a multi-lobe cam 52 is mounted on one end of the shaft 24 within the housing 50 and the first and second switches 54 and 56 (also referred to hereinafter as SW1 and SW2) cooperate with the cam 52 to provide the desired pulse signals.

More specifically, the

switches

54 and 56 may be any suitable conventional mechanically operated switches having a normally open (N.C.) contact, normally closed (N.C.) contact and a common (C.) contact. The switches may, for example, have spring loaded operating

arms

58 and 60 respectively having

rollers

62 and 64 journaled for rotation at the ends thereof. The

arms

58 and 60 may be spring biased such that the

rollers

62 and 64 follow the outer surface of the cam 52 as the cam is driven by the shaft 24 connected to the wheel 22.

The cam 52 has multiple lobes as was previously mentioned so that rotation thereof causes the contacts of the switches SW] and SW2 to open and close as the

rollers

62 and 64 follow the cam surface. In this regard, the cam 52 may be a commercially available octal (i.e. eight lobe) fluted knob adapted for mounting on a quarter inch shaft. The switches SW] and SW2 are dis posed relative to the cam 52 so that with a twelve volt d.c. signal applied to the common terminals thereof, output waveforms having the phase relationships illustrated in FIG. 2C are provided as the cam 52 rotates in one direction and then in the other direction.

For example, it may be assumed that the waveforms of FIG. 2C designated SW1 and SW2 are those desired when the cam 52 is rotating in a clockwise direction. It can be seen from FIG. 2C that the normally open and normally closed contacts of a particular switch provide a first series of pulses and an inverted form thereof (i.e. a second series of pulses 180 out of phase with the first series of pulses). If the two switches SW1 and SW2 were disposed to respond identically to the rotation of the cam 52, then the output waveforms from the nor mally open contacts of each switch would be identical and the output waveforms from the normally closed contacts of each switch would be identical. However, since it is desirable to indicate direction of rotation of the winch drum by the phase relationship between the two switch output signals, the switches SW1 and SW2 are mounted relative to the cam 52 so as to produce waveforms which are electrical degrees out of phase. With one signal as a reference waveform (e.g. the signal SW1), this 90 phase difference appears as a leading phase difference when the cam rotates in one direction and as a lagging phase difference when the cam rotates in the opposite direction, thereby providing direction information.

For example, where it is assumed that the waveforms SW] and SW2 illustrate the phase relationship for clockwise rotation of the cam 52, the signal produced by the normally open contact of SW1 leads the signal produced by the normally open contact of SW2 by 90 electrical degrees as the cam 52 rotates. If the direction of rotation of the cam 52 is reversed, the signal produced by the normally open contact of switch SWI lags the signal produced by the normally open contact of switch SW2 by 90 electrical degrees as is illustrated by the relationship between the waveforms labelled SW1 and SW2 in FIG. 2C.

Accordingly, any one or all of the series of pulses provided by the switches SW1 and SW2 may be utilized by the appropriate circuitry to provide a speed indication since all of these switch output signals are at the same frequency and that frequency is related to the speed of rotation of the winch drum. Similarly, the phase relationship between two of the output signals provided by the switches SW1 and SW2 may be utilized by the appropriate circuitry to indicate direction of rotation of the winch drum since a 90 phase relationship either leading or lagging, always exists between these output signals and reverses upon reversal of direction of rotation of the winch drum. As will hereinafter be described in greater detail, the stepper motor in the cab of the crane responds to both the frequency and phase relationship of the switch output signals and provides both a direction and a speed indication.

To facilitate an understanding of the present invention, the drum rotation indicating system of the present invention is illustrated schematically in greater detail in FIG. 3.

Referring now to FIG. 3, the signals SW1, W1, SW2 and SW2 are supplied from the respective normally open and normally closed contacts of the switches SW1 and SW2 to the display and control panel 38 in the cab of the crane. The signals SW1 and SW1 are supplied through respective

series dropping resistors

100 and 102 to a suitable amplifying circuit generally indicated at 104. Similarly, the signals SW2 and W2 are supplied through respective series current limiting

resistors

106 and 108 and a second amplifying circuit 110. Since the amplifying

circuits

104 and 110 are preferably identical, only the amplifying circuit 104 will hereinafter be described in detail.

With continued reference to FIG. 3, the current limiting resistor 100 may be connected to the base electrode of an NPN transistor 1 12 and the current limiting resistor 102 may be connected to the base electrode of an NPN transistor 114. The emitter electrodes of the

transistors

112 and 114 may be grounded and the collector electrodes thereof may be connected to the respective collector electrodes of

PNP transistors

116 and 118. The emitter electrodes of the

transistors

116 and 118 may be connected to a suitable d.c. voltage source such as the indicated 12 volt d.c. vehicle battery source.

The collector junction of the

transistors

112 and 116 may be connected to one side of a control winding 120 of a suitable conventional stepper motor 122 and through a resistor 124 to the base electrode of the transistor 118. The collector junction of the

transistors

114 and 118 may be connected to the other side of the control winding 120 and through a current limiting resistor 126 to the base electrode of the transistor 116. The stepper motor 122 may be mounted in the winch drum control handle 42, and the drive shaft 128 may be connected to drive the tactile indicator 44 as previously mentioned.

The amplifying circuit 110 may be connected to a second control winding 130 of the stepper motor 122 in the same manner as discussed in connection with the amplifying circuit 104. In addition, the signal supplied to one side of the winding 130 may be supplied through a suitable conventional isolation amplifier 132 to a conventional audio transducer 134 such as an electromagnetic speaker. The gain of the isolation amplifier 132 may be controlled in a conventional manner to control the volume of the audio transducer 134 as is generally indicated at 136. Moreover, an on-off switch may be appropriately located in the line between the signal source and the audio transducer and may be actuated by the volume control knob 136 in a conventional manner.

If desired, the signal supplied to the control winding 130 may also be applied through an isolation amplifier 140 to a suitable conventional visual speed indicator 142. For example, the visual speed indicator 142 may be a conventional frequency meter or other suitable device for providing an indication of drum speed in response to the frequency of the pulse signal. Moreover, one of the signals from the amplifying circuit 104 may be supplied to the visual speed indicator 142 so as to provide in a conventional manner an additional indication of the direction of rotation of the winch drum.

Operation The operation of the system in accordance with the present invention may be more clearly understood with reference now to FIGS. 1-3. As the operator manipulates the control lever 42 (FIG. 1) in order to raise or lower a load at the end of the hoist cable, his thumb may be placed in contact with the tactile indicator 44 when the load is not in sight. As the winch drum 10 rotates, the switches SW1 and SW2 are toggled between their normally open and normally closed positions by the cam 52 providing at least two series of pulses (e.g. at least the pulses produced by the normally open contacts of the two switches). The two series of pulses and, in the preferred embodiment, the inverted forms thereof, are supplied to the amplifying

circuits

104 and 110 in the display and control panel 38.

With the winch drum rotating in a clockwise direction, for example, the phase relationship between the two signals from the switches is that illustrated by the waveforms SW1 and SW2 in FIG. 2C. Accordingly, the control winding 120 of the stepper motor 122 is energized electrical degrees prior to the energization of the control winding 130. This may, for example, cause a corresponding clockwise rotation of the rotor and shaft 128 of the stepper motor 122, resulting in clockwise rotation of the tactile indicator 44. This clockwise rotation of the tactile indicator 44 may, for example, indicate to the operator that the load cable is running out and the load is thus being lowered.

When winch drum rotation is in a counterclockwise direction, the signals illustrated as signals SW1 and SW2 of FIG. 2C may be provided through the amplifying circuits 104 and to the stepper motor windings and 130, respectively. In this example, the control winding is energized 90 electrical degrees prior to the energization of the control winding 120 and the direction of rotation of the rotor and shaft 120 of the stepper motor 122 is accordingly reversed, e.g. is counterclockwise. The operator is thus provided with a tactile indication of counterclockwise rotation which may indicate that the cable is being brought in.

The stepper motor 122 is preferably a four wire. 33600 type two phase bidirectional stepper motor which moves approximately 1.5 per pulse. The speed of rotation of the winch drum determines the frequency of the signal supplied from the switches SW1 and SW2 and as winch drum speed increases, the frequency of the supplied signal also increases. Accordingly, the number of pulses per second supplied to the stepper 7 motor windings increases with increases in winch drum speed and the tactile indicator 44 is thus driven at a speed related to winch drum speed. Moreover, the rotor and drive shaft 128 of the stepper motor 122 are driven in a direction determined by the phase relationship between the applied signals. The operator is there fore provided with a tactile indication of both speed.

and direction of winch drum rotationv In addition, the operator may desire an audible and- /or visual indication of the speed of rotation of the winch drum. Accordingly, the operator may turn the volume control knob 136 to a desired volume, thereby closing the switch 138 and supplying the signal from the amplifier 110 to the audio transducer 134. The audio transducer 134 may thereafter produce a series of clicks which increase and decrease in rapidity in direct relation to the speed of rotation of the winch drum. The visual speed indication may be provided by the visual speed indicator 142 at all times or as desired,

It can be seen from the above that the response of the tactile indicator 44 to winch drum rotation is instantaneous regardless of the distance between the winch drum and the tactile indicator. The operator therefore knows immediately if the winch drum is rotating and also knows its speed and direction. Moreover, the operator knows with a high degree of accuracy both the point of initiation of drum rotation and, for small distances on the order of inches, the approximate amount of drum rotation.

In addition, the stepper motor 122 provides sufficient torque to permit the operator to apply a useful amount of pressure to the tactile indicator 44 while lifting and lowering loads out of visual contact. The torque is not however sufficient to shear the shaft 128 of the stepper 122 should the operator apply too great a pressure to the tactile indicator 44. If too great a pressure is applied to the tactile indicator, the stepper motor 122 may fail to rotate but no damage will be done under such circumstances. The rotor and shaft 128 of the stepper motor 122 will merely fail to rotate under such conditions of excessive pressure and will not result in damage such as cable breakage in mechanical systems.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed is:

l. A winch drum movement indicator system for providing an operator of a crane having a winch operated hoist cable with an indication of rotation of the hoist cable winch drum at an operator's station remote from the winch drum, the system comprising:

means responsive to rotation of the winch drum for generating two series of electrical pulses related in frequency to the speed of rotation of the winch drum, the two series of electrical pulses having a phase relationship related to the direction of rotation of the winch drum,

a bi-directional stepper motor responsive to said two series of pulses from said generating means and having an output drive shaft, the output drive shaft being driven at a speed related to the frequency of the two series of pulses and being driven in one di- 8 rection in response to a first phase relationship between the two series of pulses and in another direction in response to a second phase relationship between the two series of pulses; and,

a tactile indicator connected to be driven by the out put drive shaft of said stepper motor, said stepper motor and said tactile indicator being mounted on the crane at the operators station so as to provide the operator with a tactile indication of the speed and the direction of rotation of the winch drum.

2. The system of claim I wherein said generating means comprises:

first and second switch means for providing first and second pulse signals in response to the opening and closing thereof;

cam means responsive to rotation of the winch drum for opening and closing said first and second switch means at a rate related to the speed of rotation of the winch drum;

said first and second switch means;

being positioned relative to said cam means so as to provide pulses having a first phase relationship in response to rotation of the winch drum in one direction and having a second phase relationship in response to rotation of the winch drum in the other direction.

3. The system of claim 1 including control means for controlling rotation of the winch drum, said control means including a control lever handle mounted at the operators station, said stepper motor and said tactile indicator being carried by said control lever handle with said tactile indicator positioned within reach of a portion of the operators hand with the operator's hand on said control lever handle.

4. The system of claim 3 wherein said tactile indicator is mounted on the output drive shaft of said stepper motor, said stepper motor being mounted within said control lever handle.

5. The system of claim 4 wherein said generating means comprises:

cam means responsive to rotation of the winch drum for opening and closing said first and second switch means at a rate related to the speed of rotation of the winch drum; and,

said first and second switch means being positioned relative to said cam means so as to provide pulses having a first phase relationship in response to rotation of the winch drum in one direction and having a second phase relationship in response to rotation of the winch drum in the other direction.

6. The system of claim 5 including audio transducer means mounted at the operatorss station for providing an audible indication of rotation of the winch drum in response to at least one of said two series of pulses.

7. The system of claim 1 including audio transducer means mounted at the operators station for providing an audible indication of rotation of the winch drum in response to at least one of said two series of pulses.

8. The system of claim 1 wherein said tactile indicator comprises a knurled knob mounted on the output drive shaft of said stepper motor.

9. The system of claim 1 wherein said stepper motor includes first and second drive windings, said system including drive circuit means for supplying phased drive pulses to said first and second drive windings of 9 said stepper motor in response to said two series of electrical pulses.

10. The system of claim 9 wherein said generating means comprises:

first and second switch means for providing first and second pulse signals in response to the opening and closing thereof; cam means responsive to rotation of the winch drum for opening and closing said first and second switch means at a rate related to the speed of rotation of the winch drum; and, said first and second switch means being positioned relative to said cam means so as to provide pulses having a first phase relationship in response to rotation of the winch drum in one direction and having 10 a second phase relationship in response to rotation of the winch drum in the other direction.

11. The system of claim 9 including audio transducer means mounted at the operators station for providing an audible indication of rotation of the winch drum in response to at least one of said two series of pulses.

12. The system of claim 9 including control means for controlling rotation of the winch drum, said control means including a control lever handle mounted at the operators station, said stepper motor and said tactile indicator being carried by said control lever handle with said tactile indicator positioned within reach of a portion of the operators hand with the operators hand on said control lever handle.

i IOI

Claims

1. A winch drum movement indicator system for providing an operator of a crane having a winch operated hoist cable with an indication of rotation of the hoist cable winch drum at an operator''s station remote from the winch drum, the system comprising: means responsive to rotation of the winch drum for generating two series of electrical pulses related in frequency to the speed of rotation of the winch drum, the two series of electrical pulses having a phase relationship related to the direction of rotation of the winch drum, a bi-directional stepper motor responsive to said two series of pulses from said generating means and having an output drive shaft, the output drive shaft being driven at a speed related to the frequency of the two series of pulses and being driven in one direction in response to a first phase relationship between the two series of pulses and in another direction in response to a second phase relationship between the two series of pulses; and, a tactile indicator connected to be driven by the output drive shaft of said stepper motor, said stepper motor and said tactile indicator being mounted on the crane at the operator''s station so as to provide the operator with a tactile indication of the speed and the direction of rotation of the winch drum.

2. The system of claim 1 wherein said generating means comprises: first and second switch means for providing first and second pulse signals in response to the opening and closing thereof; cam means responsive to rotation of the winch drum for opening and closing said first and second switch means at a rate related to the speed of rotation of the winch drum; said first and second switch means; being positioned relative to said cam means so as to provide pulses having a first phase relationship in response to rotation of the winch drum in one direction and having a second phase relationship in response to rotation of the winch drum in the other direction.

3. The system of claim 1 including control means for controlling rotation of the winch drum, said control means including a control lever handle mounted at the operator''s station, said stepper motor and said tactile indicator being carried by said control lever handle with said tactile indicator positioned within reach of a portion of the operator''s hand with the operator''s hand on said control lever handle.

5. The system of claim 4 wherein said generating means comprises: first and second switch means for providing first and second pulse signals in response to the opening and closing thereof; cam means responsive to rotation of the winch drum for opening and closing said first and second switch means at a rate related to the speed of rotation of the winch drum; and, said first and second switch means being positioned relaTive to said cam means so as to provide pulses having a first phase relationship in response to rotation of the winch drum in one direction and having a second phase relationship in response to rotation of the winch drum in the other direction.

6. The system of claim 5 including audio transducer means mounted at the operators''s station for providing an audible indication of rotation of the winch drum in response to at least one of said two series of pulses.

7. The system of claim 1 including audio transducer means mounted at the operator''s station for providing an audible indication of rotation of the winch drum in response to at least one of said two series of pulses.

9. The system of claim 1 wherein said stepper motor includes first and second drive windings, said system including drive circuit means for supplying phased drive pulses to said first and second drive windings of said stepper motor in response to said two series of electrical pulses.

10. The system of claim 9 wherein said generating means comprises: first and second switch means for providing first and second pulse signals in response to the opening and closing thereof; cam means responsive to rotation of the winch drum for opening and closing said first and second switch means at a rate related to the speed of rotation of the winch drum; and, said first and second switch means being positioned relative to said cam means so as to provide pulses having a first phase relationship in response to rotation of the winch drum in one direction and having a second phase relationship in response to rotation of the winch drum in the other direction.

11. The system of claim 9 including audio transducer means mounted at the operator''s station for providing an audible indication of rotation of the winch drum in response to at least one of said two series of pulses.

12. The system of claim 9 including control means for controlling rotation of the winch drum, said control means including a control lever handle mounted at the operator''s station, said stepper motor and said tactile indicator being carried by said control lever handle with said tactile indicator positioned within reach of a portion of the operator''s hand with the operator''s hand on said control lever handle.