US3510107A - Multiple hoist synchronization system - Google Patents

Multiple hoist synchronization system Download PDF

Info

Publication number
US3510107A
US3510107A US697085A US3510107DA US3510107A US 3510107 A US3510107 A US 3510107A US 697085 A US697085 A US 697085A US 3510107D A US3510107D A US 3510107DA US 3510107 A US3510107 A US 3510107A
Authority
US
United States
Prior art keywords
winches
flow
hydraulic
winch
pair
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US697085A
Other languages
English (en)
Inventor
Ridley Fidler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Raytheon Technologies Corp
Original Assignee
United Aircraft Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by United Aircraft Corp filed Critical United Aircraft Corp
Application granted granted Critical
Publication of US3510107A publication Critical patent/US3510107A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C13/00—Other constructional features or details
    • B66C13/18—Control systems or devices
    • B66C13/22—Control systems or devices for electric drives
    • B66C13/23—Circuits for controlling the lowering of the load
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
    • B64D1/00—Dropping, ejecting, releasing, or receiving articles, liquids, or the like, in flight
    • B64D1/22—Taking-up articles from earth's surface

Definitions

  • I4 0 :44 may i 444
  • This invention relates to a hoist mechanism in which the speeds of a number of independently driven winch cables are synchronized in order to keep the suspended load in a fixed attitude while it is raised and lowered. Provisions are also made for individually operating the winches or operating the winches in pairs to shorten or extend the cables with respect to one another and change the attitude of the load.
  • This invention relates to a hoist mechanism in which the speeds of a number of independently driven winch cables are synchronized in order to keep a suspended load at a fixed attitude, such as a horizontal attitude, while the load is being raised or lowered.
  • winch cables operate at a uniform speed so that the attitude of the cargo is not changed while the winches are operating in unison.
  • Variations in the cable speed may arise from a number of sources.
  • the different winches may be driven at the same speed but due to the differences in the amount of cable already wound upon the winch drum, the actual radius of one winch drum may be different from that of another and consequently the speed at which the cable is paid in or out may vary.
  • different winches or groups of winches may be operated from independent motors and since the motor speeds may vary due to different loads upon the cables, the cable speeds may also vary.
  • Hoist mechanisms in which a number of cables are driven independently by separated motors are often preferred since they will permit individual operation of the cables. For example, where a load must be suspended with the paid out cable lengths being unequal, the winches at sometime must be operated individually to achieve the desired paid out lengths. Systems with individually driven cables also permit the attitude of the cargo load to be changed while the load is suspended from the cables. In addition, in aircraft systems where Weight is a critical factor, it is desirable to employ separate winch motors for remotely positioned winches instead of heavy interconnecting power shafts which might pass through intervening passageways and structural components. In multiple winch systems where the load is only moved a short distance, differences in cable speeds may not prove critical.
  • This invention relates particularly to a hoist mechanism employing a number of independently driven winches in which the speeds of the cables are synchronized to keep the suspended load in a fixed attitude while it is being raised or lowered.
  • each winch is driven by a hydraulic motor in a system in which the hydraulic power is distributed in accordance with the power demanded by the motors to keep the winches operating at a constant speed in spite of differences in the loads on each winch and motor.
  • the roportioning of hydraulic power is first made to different groups of winches and from different groups of winches to the various winches themselves. This proportioning is accomplished by hydraulic flow-dividing valves each of which include a torque motor operating a spool valve.
  • the flow-dividing valves are in turn controlled by a feedback mechanism which includes a paidout cable length transducer for each cable to produce a feedback signal varying as a function of the paid-out length of the cable.
  • the signals from the transducers are combined in an appropriate manner to proportion the proper amount of hydraulic power to the appropriate winches.
  • an electrical feedback signal representative of the paid-out cable length from one group of winches is compared with a feedback signal representative of the paid-out cable length from another group of winches.
  • the representative cable length signal is the average of the paid-out lengths from the group and in another embodiment, the representative signal is the actual paid-out length of one of the winches in the group.
  • a primary hydraulic flow-dividing valve is driven by the difference in the representative signals to proportion the hydraulic power between the group of winches. Within each group the flow is proportioned by secondary flow-dividing valves to the appropriate subgroups of winches in response to the difference in the representative paid-out cable lengths of the subgroups.
  • the hydraulic flow-dividing valves distribute the hydraulic power between the winches themselves in response to the differences in the paid-out cable lengths of the winches.
  • a high gain in the control system permits a small difference signal to operate the valves so that a fixed attitude will be maintained while the load is raised or lowered.
  • the requirement for a representative paid-out cable length signal is eliminated by providing only two hydraulic flow dividing valves which operate independently.
  • the valves drive four winches which are positioned at the corners of a parallelogram.
  • Each of the flow dividers operates one of the diagonal pairs of winches.
  • three-way valves are provided which connect the hydraulic motors directly with a hydraulic power source exclusive of the flow dividing valves.
  • Another feature of the invention is the provision for operating, or beeping, any of the winches individually or for operating selected pairs of the winches without interfering with the speed balancing system.
  • This operation of the winches permits a change of attitude of the load while the load is suspended from the winches or permits an oddly shaped load to be picked up with the actual paid-out cable lengths of the several winches being unequal.
  • Clutches are included between the paid-out cable length transducers in the feedback mechanism for each cable in order to prevent any unbalance of the biasing adjustment established by the feedback mechanisms for equalizing the speed of the winches. To prevent this adjustment from interfering with the beeping operation, the transducers are also deenergized when the clutches are disengaged.
  • FIG. 1 shows a winch-supported cargo load under a crane-type helicopter in which the hoist speed synchronization apparatus may be employed.
  • FIG. 2 is a plan view of the crane-type helicopter showing the position of four hydraulically driven winches.
  • FIG. 3 is a detail drawing of one of the winches including a hydraulically driven motor and paid-out cable length potentiometer.
  • FIG. 4 is a diagram of the hydraulic system which drives the winch motors.
  • FIG. 5 is a schematic of the hydraulic flow-dividing valves in the hydraulic system of FIG. 4.
  • FIG. 6 is an electrical diagram of the control system which achieves speed synchronization of the four winch motors in FIG. 4.
  • FIG. 7 is an electrical diagram of a simplified control system which achieves speed synchronization of the four winches in FIG. 4.
  • FIG. 8 shows the hydraulic system which employs only two flow-dividing valves for a four-point hoist systern.
  • FIG. 9 is a simplified electrical diagram of the control system which achieves speed synchronization of the fourpoint hoist system in FIG. 8.
  • FIG. 10 depicts the load C.G. limitations imposed by the hoist system of FIG. 8.
  • a crane-type helicopter is seen having a fuselage 10, a motor 12 driving a rotor 14 through a transmission 16.
  • a forward landing gear 18 is connected to cockpit 20 and since the helicopter is of the crane-type, it has an elongated rear landing gear 22 and 24 projecting downwardly from laterally extending struts 26 and 28.
  • a cargo load 30 Suspended between the rear landing gear from the fuselage is a cargo load 30.
  • the cargo load may be a pallet having a load fastened thereon, or a bulk container, or a passenger pod for transporting personnel.
  • Cargo load 30 is suspended from the fuselage 10 by means of isolators 32, 34, 36 and 38 and winches 40, 42, 44 and 46.
  • isolators 32, 34, 36 and 38 For a further description of the isolators and the pod positioning and supporting means, reference may be had to -U.S. Pats. Nos. 3,176,939 and 3,176,940.
  • the winches employed in the present invention have been modified slightly from those described in the above-referenced patents; however, the isolators and the supporting lengths may be the same.
  • winches for raising and lowering the cargo load from the fuselage 10 of the helicopter.
  • the winches operate at essentially the same speed so that when the helicopter is raising or lowering the cargo load while in a hovering condition, the altitude of the cargo would not change as the distance between the helicopter and the ground is traversed.
  • provisions be included to individually operate the winches so that all loads can be drawn close to the fuselage at an altitude most suitable for high speed flight under the helicopter.
  • FIG. 3 shows a detail configuration of the winch which is the same for all four winches.
  • the winch 40 has a housing which would be supported through the isolators in the helicopter embodiment.
  • a winch cable 52 is wound upon the winch drum 54.
  • the winch drum 54 has an external helical groove in which the paid-in portion of the cable is nested.
  • the one end of the cable 52 is firmly attached to the drum and the other end of the cable 52 has an appropriate attaching device such as a hook (not shown) hanging pendantly over a scrub roller 56.
  • the roller serves as a guide for the cable 52 as it is paid in or out from the drum 54.
  • a hydraulic motor 58 is connected to the winch housing and since such motors generally operate at a high speed, a suitable gear reduction unit may be incorporated within the drum 54 to reduce the operating speed of the drum on the axis 60 and increase the driving torque. If desired, a self-actuated brake may be incorporated in the drive train between the hydraulic motor 58 and the drum 54 in order to lock the drum at a fixed position whenever the motor is not operating.
  • the hydraulic motor 58 is a conventional, reversible, fixed displacement hydraulic motor. In such motors, the rotational displacement of the motor is directly proportional to the quantity of fluid displaced by the motor and the direction of rotation is reversed when the direction of flow is reversed. If constant motor speeds are to be maintained, a larger load on a motor will require more hydraulic power than a small load. Conversely, a small load on the motor will require less hydraulic power. With motor rotation proportional to fluid displacement, motor speed remains proportional to fluid flow rate. At constant motor speed, therefore, the power must be varied by changing the pressure differential across the motor.
  • a cable length potentiometer 62 mounted within a section of the housing 50.
  • the potentiometer 62 is connected to a gear 64 which is driven from a gear 66 connected to and rotating with the drum 54.
  • the potentiometer is a conventional high precision linear transducer of the type shown in US. Pat. 3,331,047 which, when excited by DC voltage, produces an electrical signal varying in proportion to the length of cable paid in or out.
  • a suitable potentiometer might have a ten-turn rotary wiper, a total resistance error of /2%, a linearity error of .03% and resolution error of .03%.
  • a conventional magnetic particle clutch 68 Interposed between the gear 64 and potentiometer 62 is a conventional magnetic particle clutch 68.
  • the clutch 68 is engaged when an electrical signal is applied and disengaged when the electrical signal is removed.
  • the potentiometer 62 therefore, will be connected to rotate with the drum 54 when the clutch 68 is engaged.
  • the potentiometer will produce an electrical signal which varies linearly as the drum 54 rotates and cable is paid in or out. When the clutch is disengaged, the drum may rotate and pay cable in or out Without changing the signal generated by the potentiometer.
  • FIG. 4 will show the hydraulic system by which the four remotely positioned winches are powered.
  • the hydraulic motors 58, 70, 72 and 74 are connected respectively to the winches 40, 42, 44 and 46. Hydraulic power in the form of pressurized hydraulic fluid is produced by the winch pump 78.
  • the winch pump 78 normally delivers a constant flow of hydraulic fluid at a variable pressure but the rate of flow and direction of flow can be varied through an electrically actuated control valve 80.
  • the pump 78 supplies hydraulic fluid to the motors 58, 70, 72 and 74 through either conduit 82 or 84 depending on the direction of flow established by the control valve 80. Since the hydraulic motors 58, 70, 72 and 74 are the reversible fixed displacement type, the direction of operation of the motors, and therefore the winches, will be determined by the control valve 80.
  • Filters 86 and 88 are included in the conduits 82 and 84.
  • Check valves 90 surrounding the filter 86 and the check valves 92 surrounding the filter 88 ensure that the hydraulic flow will always pass in the same direction through the filters to avoid back-washing the filters when the direction of the hydraulic flow is reversed.
  • a pressurereducing valve 94 is also included between the conduits 82 and 84 to bypass excessive pressure from the high pressure side to the low pressure side of the hydraulic system.
  • the check valves 96 connecting the pressure-reducing valve 94 between the conduits 82 and 84 ensure that the valve 94 will experience a positive pressure differential in the proper direction for actuation of the valve.
  • a shutoff valve 98 is included in conduit 84 to shut off the motors.
  • valves 100, 102 and 104 Interposed between the shutofl valve in conduit 84 and the motors 58, 70, 72 and 74 are flow-dividing valves 100, 102 and 104. It is important to note that the hydraulic valve 100 controls the flow in the two conduits 106 and 108. The valve 102 in turn controls the flow through conduits 110 and 112 while the valve 104 controls the flow through conduits 114 and 116. The total flow in conduits 110 and 112 passes through the valve 100 and conduit 106. The total flow through conduits 114 and 116 passes through valve 100 and conduit 108. The distribution of the flows through these valves and conduits is controlled by the valves regardless of the direction of flow through the motors 58, 70, 72 and 74 and the conduits 82 and 84.
  • the hydraulic system between the winch pump and the motors is a closed hydraulic system and since there is no reservoir in this system it may be necessary from time to time to add additional hydraulic fluid lost through leakage.
  • This is accomplished through a replenishing pump 118 which draws fluid from a reservoir 120.
  • This pump may be any suitable pump and in the helicopter installation it can be a pump which supplies utility pressure for operating the landing gear and other auxiliary devices on the aircraft.
  • fluid is taken through a pressure reducer 122 which reduces the pressure to approximately 50 p.s.i. and directs the fluid either through check valve 124 in replenishing line 126 or check valve 128 in replenishing line 130 to the conduits 82 or 84, respectively.
  • the check valves are incorporated in lines 126 and 130 so that the high pressure fluid from the winch pump 78 will not be lost through the replenishing system.
  • the pressure on the return side of the winch pump drops below the 50 p.s.i. pressure established by the pressure reducer 122, fluid will be added to the hydraulic system powering the winches.
  • either one of the conduits 82 or 84 may serve as the return line to the pump 78, and consequently the two replenishing lines 128 and 130 are necessary.
  • the replenishing pump 118 can also supply the control pressure for the control valve '80 which varies the flow delivered by the winch pump 78.
  • the replenishing pump 118 can also supply fluid through a flow reducing orifice 132 and drain line 134 to the reservoir 120 for cooling the winch pump 78.
  • a pressure reducer 136 between the high. pressure side of the replenishing pump 118 and the drain line 134 prevents excessively high pressures from damaging the winch pump.
  • a filter 13 8 is also included to prevent contamination from affecting either the control valve or the orifice 132 and also prevents dirt from entering the hydraulic system for the winches.
  • the hydraulic flow-dividing valves 100, 102 and 104 ensure that the hydraulic flaws through each of the hydraulic motors 58, 70, 72 and 74 remain the same regardless of the power demanded by each of the motors.
  • the valves are similar in construction to the conventional electro-hydraulic servo valves which have a torque motor operating a flapper valve to control a spool Valve.
  • the flow-dividing valve is seen in greater detail in FIG. 5.
  • hydraulic control fluid from the replenishing pump 118 of FIG. 4 enters a port 140 and pases through a filter 142, through the orifices 144 and 146 and into control ducts 148 and 150, respectively.
  • control ducts direct the fluid through nozzles 152 and 154 against a flapper 156 which is positioned in close relationship to each of the nozzles 152 and 154. Fluid which passes through the nozzles 152 and 154 is returned to the low pressure side of the replenishing pump 118 through conduit 176.
  • the flapper 156 is caused to move closer to one nozzle or the other by a torque motor 158 which includes two electromagnetic coils 160 and 162 operating upon an armature 164 to which the flapper 156 is connected.
  • a torque motor 158 which includes two electromagnetic coils 160 and 162 operating upon an armature 164 to which the flapper 156 is connected.
  • a corresponding decrease in the control pressure in duct 150 will occur because the flow will increase through the nozzle 154 and cause a corresponding increase in the pressure drop across orifice 146.
  • the increase in the pressure in duct 148 and the decrease in the pressure in duct 150 will develop a pressure ditierential across the spool valve will restrict hydraulic flow for the winch motors passing between the dual ports 168 and 170 and the single port 172.
  • the summation of the flow through ports 168 and 170 will equal the total flow through the port 172. This relationship remains true regardless of whether the flow enters the valve through single port 172 and is divided between dual ports 168 and 170 or if the flow is in the reverse direction from ports 168 and 170 to port 172.
  • the spool acts as a variable orifice for the ports 168 and 170 which biases the hydraulic power converted by the winch motors to maintain constant speeds in spite of differences in the loads on the winches.
  • the spool shown in the schematic of FIG. 5 is slightly underlapped in that the lands of the spool 166 do not obstruct any portion of the ducts 168 or 170 when the spool is in the normally centered position. Hydraulic flow will only be reduced in one of the ports 168 or 170 when the spool moves away from its centered position.
  • valve could be constructed with overlapping lands and ports so that a displacement of the spool from the normally centered position will not only reduce the flow through the one port but will also increase the flow through the other port.
  • the disadvantage of the overlapped valve is that a greater power loss will occur when the valve is in its normally centered position due to the restrictions on each of the ports in the centered condition.
  • a feedback spring 174 connects the valve spool 166 to the flapper 156.
  • the spring 174 ensures that the position of the spool 166 will vary in direct proportion to the position of the flapper valve between the nozzles 152 and 154.
  • the position of the flapper 156 when it is centrally located between the nozzles 152 and 154 should correspond with a central position of the spool 166- on the two ports 168 and 170 in which case the flow through each of these ports will be balanced.
  • This balanced flow condition through the ports 168 and 170 in turn corresponds approximately with balanced control currents through the electromagnetic coils 160 and 162 of the torque motor 158.
  • FIG. 6 The control system by which the flow-dividing valves 100, 102 and 104 are operated in response to the cable length potentiometers on the winches is shown in FIG. 6.
  • the winches 40, 42, 44 and 46 are shown in positions which correspond generally to the positions of the winches in FIG. 2. where the helicopter is viewed from above.
  • the forward pair of winches 40 and 42 are located to the left of FIG. 6 and the rear pair of winches 44 and 46 are located on the right.
  • the clutch 68 described in FIG. 3 connects the winch 40 to the cable length potentiometer 62.
  • clutches 180, 182 and 184 connect the winches 42, 44 and 46 to potentiometers 186, 188 and 190, respectively.
  • the potentiometers are transducers which have wipers 192, 194, 196 and 198 varying the resistance of the potentiometers to develop voltages for controlling the flow-dividing valves 100', 102 and 104.
  • the excitation for the potentiometers is a 28 volt power source in the helicopter, and is transmitted through switches 200, 202 and 204.
  • the conductors 206 and 208 lead from the separate contacts of switch 204 to opposite ends of the resistive elements in the potentiometers in order to reverse the excitation of the potentiometers.
  • Switch 204 when in one position, therefore, will energize the one end of the potentiometers while the opposite end is floating. When the switch 204 is in the other position, the energized and floating ends are reversed. The reason for this reversible excitation will be explained in greater detail below.
  • the wipers 192 and 194 of the potentiometers 62 and 186 are operated respectively by the forward pair of winches 40 and 42.
  • the signals from the potentiometers 62 and 186 are applied to a large, grounded input impedance in comparator 210 in order to obtain a phase sensitive difference signal representative of the difference in the voltages from the two potentiometers 62 and 186.
  • the plus and minus signs indicate that the positive value of the signal from the potentiometer 62 is compared with the negative value of the signal from potentiometer 186.
  • the input impedance to the comparator should be high compared with the total impedance of the potentiometer in order to maintain a linearity of the input signals with the position of the wiper.
  • linearity could also be ensured by exciting the potentiometers with a 28 volt signal across the full resistor of the potentiometers rather than having one end of the potentiometers floating.
  • the comparator 210 therefore produces a null signal when the values of the voltages from potentiometers 62 and 186 are the same and this null signal is impressed upon the coils of flow-dividing valve 102 which proportions the flow between the hydraulic motors for the forward pair of winches 40 and 42.
  • the comparator 210 would produce an unbalanced electrical signal representing the difference in the voltages derived from the potentiometers 62 and 186 and bias the hydraulic power applied to the winches 40 and 42 by moving the valve spool to increase or decrease the openings of the dual ports of the flow-dividing valves in accordance with the magnitude of the unbalanced signal.
  • the movement of the valve spool will generally open the port of the flow-dividing valve which is passing the smaller of the flow rates. This arises from the fact that the winch which is operating at the slower speed will cause the movement of the wiper connected thereto to fall behind the movement of the wiper on the opposite winch controlled by the same flow-dividing valve. As a result, the difference signal generated by the comparator 210 will increase and cause a further increase in the hy draulic power bias to the winch which is operating at the slower speed. An equilibrium condition will be established when the wipers move along the potentiometers at the same speed and at a fixed differential, as measured by the comparator 210'. The power bias to the winches will be stabilized and therefore the winches will continue to operate at the same speed. In this condition, the flow rates to the two winches will be the same regardless of the difference in the power demanded by the two winches 40 and 42.
  • the control system of FIG. 6 will not only synchronize the speed of the winches but will synchronize the speed of the winches at an attitude of the load at which the paid-out cable lengths of the winches are practically equal as sensed by the potentiometers.
  • the suspended load can be held in a level attitude while it is raised or lowered from the helicopter.
  • a very small difference in the paid-out cable lengths will produce a large error signal from the comparator 210* and cause the flowdividing valve to speed up the lagging winch until the small differential is essentially eliminated.
  • the proportioning of the hydraulic flow between the rear pair of winches 44 and 46 is accomplished in a manner similar to the proportioning between the forward pair of winches.
  • the winches 44 and 46 operate the potentiometers 188 and 190 having wipers 196 and 198 which drive a comparator 212 and the flow-dividing valve 104.
  • the switch 204 also reverses the energization of the potentiometers 188 and 190 to reverse the phase of the error signal for the flow-dividing valve 104. Switch 204 is operated when the direction of operation of the winch motors is changed to raise or lower the cargo load.
  • the flow-dividing valves 102 and 104 can level the load with respect to the lateral axis of the aircraft.
  • a signal must be derived from the potentiometers to control the flow-dividing valve which proportions the flow between the fore and aft pairs of winches. This is accomplished by deriving representative paid-out cable length signals for the fore and aft cables from the averaging networks 214 and 216 respectively.
  • the averaging network 214 adds the signals from the potentimeters 62 and 186 operatively associated with the forward pair of winches 40 and 42.
  • the signal derived from the averaging network 214 therefore is proportional to the average paid-out cable length of the forward pair of winches or the average distance between the cargo load and the one pair of winches.
  • a signal proportional to the average paid-out cable length of the rear pair of winches 44 and 46 is derived from the averaging network 216.
  • the flow-dividing valve 100 consequently, proportions the hydraulic power between the forward and rear pairs of winches in accordance with the difference in the averages of the paid-out cable lengths of the forward and rear pairs of winches.
  • This proportioning of the hydraulic power can be thought of as the process for synchronizing the average speed of the forward pair of winches with the average speed of the rear pair of winches in accordance with the difference in the average distance between the cargo load and the forward pair of winches and the average distance between the cargo load and the rear pair of winches. This synchronization occurs in spite of dilferences in the power demanded by the winches to maintain equal speeds.
  • a high gain of comparator 218 will operate the flow-dividing valve 100 in response to a small difference in the signals from averaging networks 214 and 216. Such a gain will keep the cargo load substantially level with the longitudinal axis of the helicopter as the average speeds of the winches are synchronized.
  • the phase of the error signal from the comparator 218 will also be reversed when the switch 204 reverses the energization of the transducers. This operation will be necessary whenever the direction of operation of the winches is reversed as mentioned above.
  • the operation of the flow dividing valves may be more clearly understood by an explanation of their functions.
  • the ports 168 and 170 are always open when the valve is in its neutral position. In this condition, the pressure drops across the ports would be equal. If one of the winch motors must operate at a greater power level in order to maintain synchronous speed, the difference in the cable lengths of the winches developed by a ditference in speed will energize the proportioning of valve and cause the ports 168 and 170 to open and close correspondingly and change the pressure drops across the ports until the proper power bias to the respective winch motors or pairs of winch motors is established. At this point the flows through the ports and the winch speeds will be the same.
  • the flow-dividing values control the flow proportioning and the power distribution between the Winches regardless of the direction of fluid flow in the hydraulic circuit.
  • the ports of the flow divider valves are trimmed to pass balanced hydraulic power and biased by the cable angle transducers to provide balanced hydraulic flows.
  • the winches may be operated individually or in selected pairs in order to change the attitude of the load while it is suspended from the winches or to extend or retract certain of the winch cables without operating the others.
  • the potentiometers associated with each of the winch cables establish a power bias to the winches which will synchronize the speed of the winches in spite of variations in the load carried by each of the winches. It will be readily recognized that the individual operation of any of the winch cables would unbalance this power bias unless the potentiometers were disengaged from the cables during the individual operation, beeping, of the cables. It is for this reason that the electromagnetic clutches are incorporated between each of the winches and wipers of the potentiometers.
  • switches 220, 222, 224 and 226 are included to deenergize the clutches respectively associated with the wipers 192, 194, 196 and 198.
  • switch 220' which is typical of any one of these switches, it will be noted that when the switch is actuated electrical power derived through switch 228 and switch 230 will be removed from the clutch 68 to disengage wiper 192 from the winch 40.
  • this electrical power will be applied as a 28 volt signal to both the comparator 210 and the averaging network 214 in order to introduce a maximum bias signal to flow-dividing valves 102 and 100.
  • This maximum bias signal in valve 102 will completely close the port of the valve 102 to the winch 44.
  • the maximum bias signal applied to the averaging network 214 and comparator 218 will completely close off the port of valve for the rear pair of winches 44 and 46. Consequently, the only winch which will operate when hydraulic power is turned on will be winch 40.
  • the signals from the potentiometers may also interfere with the bias signal derived from switch 220 for beeping the winch 40. For this reason, a separate set of contacts associated with each of the switches 220, 222, 224 and 226 will be broken at the time any one of these switches is actuated to deactivate relay 232 and deenergize all of the potentiometers. It will, therefore, be understood that operation of any one of the switches 220', 222, 224 or 226 for beeping the winch motors will electrically deenergize all potentiometers, disengage the wipers from the winches and energize the flow-dividing valves to direct hydraulic fluid to the winch which is to be beeped.
  • the direction in which the winches will operate during beeping will depend solely upon the winch pump which is controlled by the servo valve 80. It may be desirable to have several fixed flow rates to which this control valve can be set in order to establish a reduced flow from the winch pump when individual winches are beeped and prevent overspeeding of the hydraulic motors receiving the entire output of the winch pump.
  • the fore or aft pairs of winches can be operated independently. This is accomplished by the ganged switches 230 and 234 operated by solenoid 236 and ganged switches 238 and 240 operated by solenoid 242. When switch 244 is opened, solenoid 236 is deenergized and the clutches 68 and for winches 40 and 42 are deenergized as well as all of the potentiometers. A beeping signal is applied to the comparator 210 and the averaging network 214. The application of the beeping signals to the comparator 210 will balance the power bias established by the flow-dividing valve 102.
  • the signal produced by the averaging network 214 will bias the comparator 218 so that the aft pair of winches will be shut off and all hydraulic power will be directed to the forward pair of winches 40 and 42.
  • solenoid 236 When solenoid 236 is deenergized, therefore, the forward pair of winches will be operated together and the rear pair of winches will remain stationary.
  • Solenoid 242 together with the switches 238 and 240 perform the identical function for the rear pair of winches so that when the switch 246 is opened and solenoid 242 is deenergized, only the rear pair of winches 44 and 46 will be operated.
  • Switch 248 actuates solenoid 250 to apply power to the entire speed synchronization system. It may be desirable, for example, if a failure occurs in the speed synchronization system to deenergize the system by opening the switch 248 and deenergizing solenoid 250. In this case, the feedback springs in the flow-dividing valves tend to position the flappers and spools in their central position so that the ports through the valves are opened and the winches operate at approximately the same speed provided the cargo load has a center of gravity located substantially equidistant from the contact points of all of the winches.
  • FIG. 7 A simplified embodiment of the electrical controls is seen in FIG. 7.
  • the comparators 210, 212 and 218, and the averaging networks 214 and 216 have been eliminated.
  • the resistive elements of the potentiometers are excited across their entire length from switch 204.
  • the signals from the cable length potentiometers are fed directly to the coils of the torque motors in the flow dividers. Essentially, the signals comparison is made by the torque motor coils themselves.
  • potentiometer 260 has been added to one of the forward cable winches and potentiometer 262 has been added to one of the rear cable winches.
  • potentiometers are used to generate representative cable length signals for driving the primary flow dividing valve 100.
  • the representative signal is equal to the cable length signal from only one of the winches.
  • speed synchronization between the forward pair or rear pair of winches is provided by the flow divider valves 102 and 104, the cable length signal from one of the forward winches and one of the aft winches will be acceptable to synchronize the forward and aft winch speeds.
  • these additional potentiometers would be connected to the winches through the clutches 180 and 184 respectively (FIG. 1) as well as the potentiometers 186 and 190.
  • the beeping system includes individual switches 264, 266, 268 and 270 which actuate relays 272, 274, 276, and 278, respectively.
  • the relays disconnect the potentiometers from flow dividers 102 and 104 and apply a 28 volt signal directly to the one coil of the torque motors to fully bias the flow divider toward one of the Winch motors.
  • the switches also actuate one of the double relays 280 or 282 to fully bias the main flow divider valve 100 to the corresponding fore or aft pairs of winches.
  • the double relay is actuated, the energization of the potentiometers is removed through ganged switches 284 or 286. In this manner, any one of the winch motors can be operated individually. It will be readily understood that they can also be operated in pairs by gauging the switches 264, 266, 268 and 270 or by inserting additional ganged switches in series with the above switches.
  • FIGS. 8 and 9 Still another embodiment of my invention is shown in FIGS. 8 and 9.
  • two flow dividers 300 and 302 are employed to control the fiow rates between the four winch motors 58, 70, 72 and 74 previously described with respect to FIG. 4.
  • the flow divider 300 acts as a fiow proportioner for the diagonally paired winch motors 58 and 74 while the flow divider 302 acts as a proportioner for the diagonally paired motors 70 and 72.
  • the flow dividers operate independently but will move the load, within limitations defined below, at a synchronous speed.
  • three-way valves 304, 306, 308 and 310 are interposed between the respective winch motors and the flow dividing valves 300 and 302. These three-way valves have a passageway connecting the hydraulic motor with its respective flow dividing valve and a passageway which connects the motor to the hydraulic pump 78 through a bypass line 312 exclusive of the flow dividing valves.
  • Each of the three-way valves can be actuated between two positions to correspondingly open and close the respective passages. When any one of the winches is to be operated by itself, the corresponding three-way valve will be actuated to its bypass position to connect the motor with bypass line 312 and the shutoff valve 98 will be closed to prevent any of the other winch motors from operating.
  • FIG. 9 The control schematic for the diagonally paired winches is shown in FIG. 9 in simplified form. It will be understood that the same clutches incorporated with the potentiometers in FIG. 6 would be actuated during the beeping operation described above. It will be readily noticed that no representative paid out cable length signal is required with only two flow dividing valves connected as shown because each of the valves 300 and 302 operate independent groups of winches. Because of this independence, limitations must be imposed on the location of the load center of gravity (C.G.) within the parallelogram defined by the cables 314, 316, 318 and 320 depicted in FIG. 10. The locus of points within which the C.G. of the load can lie is the shaded area between the lines connecting the mid-points of the sides of the parallelogram.
  • C.G. load center of gravity
  • Apparatus for moving a cargo from one position to another comprising:
  • controllable motor means connected to the winches for individually driving each of the winches
  • control means connected to the controllable motor means for equalizing the speed of the cables in response to the sensing means.
  • controllable motor means includes a hydraulic motor for each winch
  • control means connected to the controllable motor means includes a plurality of hydraulic flowdividing valves which distribute hydraulic flow to the motors to equalize the speed of the cables.
  • Apparatus according to claim 2 which includes:
  • Apparatus for raising and lowering a load at a fixed attitude comprising:
  • a speed synchronization control for two pairs of independently and hydraulically driven winches with cables comprising:
  • a first hydraulic flow distribution valve having a fluid communication with each of the pairs of winches and controllable to vary the hydraulic flow through each pair, the valve being connected to the signal generating means and responsive to the second set of signals;
  • a four-point hoisting mechanism comprising:
  • fifth means are operatively connected to the first, second, third and fourth means for proportioning the power between the second and fourth means in response to the first and third means.
  • the second, fourth and fifth means include valves which proportion hydraulic fluid flow between the hydraulically driven hoists.
  • a four-point hoist mechanism for a cargo carrier comprising:
  • a second controllable hydraulic flow-dividing valve is interposed between the first hydraulic flow-dividing valve and the one pair of winches and connected to the sensors associated with the cables of the one pair of winches, the valve dividing the hydraulic flow between the one pair of winches in response to the signals from the sensors.
  • Apparatus for synchronizing the speeds of two pairs of winch cables, each cable being independently operated by a hydraulically driven winch for lifting a load comprising:
  • a first controllable hydraulic power distribution valve having a fluid communication with the hydraulic power source and connected to the winches operating the one pair of cables for distributing hydraulic power from the source between winches for the one pair, the valve also being connected to the first means and responsive to the first control signal, whereby the power distribution is controlled by the difference in the cable lengths of the one pair;
  • a second controllable hydraulic power distribution valve having a fluid communication with the hydraulic power source and connected to the winches operating the other pair of cables for distributing hydraulic power from the source between winches for the other pair, the valve also being connected to the second means and responsive to the second control signal, whereby the power distribution is controlled by the difference in the cable lengths of the other pair.
  • Apparatus according to claim 14 further includmg:
  • each sensor is a transducer having a movable element associated with a cable for varying the sensor signal
  • disengageable clutches are interposed between the movable elements and the respective cables; and (c) means are provided for individually disengaging clutches whereby the speed synchronization signals established by the disengaged sensors are unaffected by movement of the respective cables.
  • each hydraulically driven winch includes a reversible hydraulic motor to operate the winch
  • the hydraulic source includes a reversible flow pump for changing the direction of operation of each motor and the driven winch.
  • each sensor is an electromechanical transducer developing an output signal from an excitation voltage in response to the paid-out cable length
  • the first means and the second means each employ a signal comparator producing a phase-sensitive difference signal from the output signals of the sensors;
  • the first and second controllable hydraulic power distribution valves bias the hydraulic power between the winches as a iunction of the phase of the diiference signal from the comparators;
  • (d) means are provided for reversing the excitation voltage on the transducers to permit the phase of the difference signal and the hydraulic power bias to the winches to be reversed when the direction of operation of the motors is reversed.
  • a four-point hoist mechanism comprising:
  • first speed control means connected to the sensors for synchronizing the speeds of the Winches Within each pair in response to the signals from the sensors within the respective pairs;
  • second speed control means connected to the sensors for synchronizing the speed of the first pair of winches with the speed of the second pair of winches in response to sensor signals from 'both the forward and aft pairs of winches whereby the load can be raised and lowered from the helicopter at the synchronized speed of the winches.
  • the second speed control means includes a first hydraulic flow-dividing valve which proportions hydraulic flow between the first pair and the second pair of winches;
  • the first speed control means includes:
  • each bydraulic flow-dividing valve has two variable and coacting hydraulic flow ports trimmed to pass balanced hydraulic power and biased by the sensors to provide balanced hydraulic flows whereby the fixed displacement hydraulic motors drive the winches at a synchronous speed in spite of the dilferences in power required to drive the different winches.
  • each sensor is an electrically energized transducer having an adjustable element disengageably connected to the winch to vary the sensor signal with movement of the cable;
  • (b) means are provided for simultaneously deenergizing all sensors, disengaging the adjustable element of a sensor operatively associated with a selected winch, and energizing the first and second speed control means to operate the selected winch individually without unbalancing the bias adjustment previously established by the sensors.
  • each sensor is an electrically energized transducer having an adjustable element disengageably connected to the winch to vary the sensor signal with movement of the cable;
  • (b) means are provided for simultaneously deenergizing all sensors, disengaging the adjustable elements of the sensors operatively associated with a selected pair of the winches, and energizing the first and second speed control means to operate the selected pair without unbalancing the bias adjustment previously established by the sensors.
  • a four-point hoist system comprising:
  • transducers connected to each of the cables for generating signals proportioned to the length of cable paid out by the winches
  • Apparatus according to claim 26 further including three-way hydraulic valves interposed between each of the hydraulic motors and the respective propoitioners each valve having a closable series passage connecting 17 18 the respective proportioner and the motor and a ciosable FOREIGN PATENTS bypass passage communicating the motor with the source 742,094 9/1966 Canada exclusive of the proportioner.

Landscapes

  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Mechanical Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
US697085A 1968-01-11 1968-01-11 Multiple hoist synchronization system Expired - Lifetime US3510107A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US69708568A 1968-01-11 1968-01-11

Publications (1)

Publication Number Publication Date
US3510107A true US3510107A (en) 1970-05-05

Family

ID=24799725

Family Applications (1)

Application Number Title Priority Date Filing Date
US697085A Expired - Lifetime US3510107A (en) 1968-01-11 1968-01-11 Multiple hoist synchronization system

Country Status (3)

Country Link
US (1) US3510107A (pt)
BR (1) BR6905495D0 (pt)
GB (1) GB1247928A (pt)

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3743107A (en) * 1970-08-04 1973-07-03 J Verschoof Device for preventing a body depending from ropes from swinging
US3838836A (en) * 1973-08-08 1974-10-01 Calspan Corp Method and apparatus for load stabilization in heavy lift helicopters
US4088304A (en) * 1975-02-25 1978-05-09 O & K Orenstein & Koppel Aktiengesellschaft Winch system control mechanism for the simultaneous control of two winch motors
US4090567A (en) * 1976-10-26 1978-05-23 Tomlinson Francis E Fire fighting helicopter
US4244561A (en) * 1979-07-02 1981-01-13 The United States Of America As Represented By The Secretary Of The Army Airborne hoist
US4457424A (en) * 1981-08-03 1984-07-03 Wuensch Charles L Apparatus for loading and unloading vehicles
US20030057597A1 (en) * 2000-03-03 2003-03-27 Aimo Seppanen Method and plant for manufacturing prestressed concrete products
WO2007132454A2 (en) * 2006-05-11 2007-11-22 Olive Engineering Ltd. Aircraft with cables to deploy hanging cabin
WO2008085547A3 (en) * 2006-07-27 2008-11-06 Sikorsky Aircraft Corp Aerodynamic integration of a payload container with a vertical take-off and landing aircraft
US20100065691A1 (en) * 2008-09-12 2010-03-18 Droney Christopher K Modular externally accessible batteries for an aircraft
US20100178176A1 (en) * 2009-01-09 2010-07-15 Jeremy Kenyon Retractable Pump System
US20100222993A1 (en) * 2005-06-24 2010-09-02 Sikorsky Aircraft Corporation System and method for improved rotary-wing aircraft performance with interior/external loads
US20130277074A1 (en) * 2010-09-29 2013-10-24 Ramon Corujo Pardo Fire extinguishing device
US20140217230A1 (en) * 2013-02-05 2014-08-07 Biosphere Aerospace, Llc Drone cargo helicopter
US9333379B2 (en) 2012-01-27 2016-05-10 Simplex Manufacturing Co. Aerial fire suppression system
US20160280372A1 (en) * 2015-03-25 2016-09-29 Nolan Russell Poness Craned air transporter
US9676481B1 (en) 2015-03-27 2017-06-13 Amazon Technologies, Inc. Tether compensated airborne delivery
US9688404B1 (en) * 2014-12-02 2017-06-27 Amazon Technologies, Inc. Stabilized airborne drop delivery
US10112810B2 (en) * 2014-02-11 2018-10-30 R. Stahl Schaltgerate Gmbh Lifting hoist with hysteresis clutch
US10406390B2 (en) 2016-08-09 2019-09-10 Simplex Manufacturing Co. Aerial fire suppression system
CN111003183A (zh) * 2018-10-05 2020-04-14 极光飞行科学公司 用于自主物体拾取的地面操作
US20200331603A1 (en) * 2018-06-28 2020-10-22 Justin Wesley Green Unmanned coaxial rotor aerial vehicle for transport of heavy loads
WO2020219818A1 (en) * 2019-04-24 2020-10-29 Breeze-Eastern Llc Hoist system and process for sway control
EP3774431A4 (en) * 2018-04-04 2021-12-29 Terex South Dakota, Inc. Hydraulic drivetrain for a utility vehicle
US11447248B2 (en) * 2017-12-21 2022-09-20 Elroy Air, Inc. Unmanned vehicle cargo handling and carrying system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1419641A (en) * 1972-03-21 1975-12-31 Lucas Industries Ltd Control apparatus for a powered hoist
US8755187B2 (en) 2006-06-02 2014-06-17 Siemens Industry, Inc. Systems, devices, and methods, including a basepan comprising a banding stud for increasing current carrying capacity

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2957582A (en) * 1958-05-07 1960-10-25 Carroll B Lusk Grid structures

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2957582A (en) * 1958-05-07 1960-10-25 Carroll B Lusk Grid structures

Cited By (44)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3743107A (en) * 1970-08-04 1973-07-03 J Verschoof Device for preventing a body depending from ropes from swinging
US3838836A (en) * 1973-08-08 1974-10-01 Calspan Corp Method and apparatus for load stabilization in heavy lift helicopters
US4088304A (en) * 1975-02-25 1978-05-09 O & K Orenstein & Koppel Aktiengesellschaft Winch system control mechanism for the simultaneous control of two winch motors
US4090567A (en) * 1976-10-26 1978-05-23 Tomlinson Francis E Fire fighting helicopter
US4244561A (en) * 1979-07-02 1981-01-13 The United States Of America As Represented By The Secretary Of The Army Airborne hoist
US4457424A (en) * 1981-08-03 1984-07-03 Wuensch Charles L Apparatus for loading and unloading vehicles
US20030057597A1 (en) * 2000-03-03 2003-03-27 Aimo Seppanen Method and plant for manufacturing prestressed concrete products
US6841110B2 (en) 2000-03-03 2005-01-11 Addtek Research Development Oy Ab Method and plant for manufacturing prestressed concrete products
US20100222993A1 (en) * 2005-06-24 2010-09-02 Sikorsky Aircraft Corporation System and method for improved rotary-wing aircraft performance with interior/external loads
US7954766B2 (en) * 2005-06-24 2011-06-07 Sikorsky Aircraft Corporation System and method for improved rotary-wing aircraft performance with interior/external loads
WO2007132454A2 (en) * 2006-05-11 2007-11-22 Olive Engineering Ltd. Aircraft with cables to deploy hanging cabin
WO2007132454A3 (en) * 2006-05-11 2009-02-26 Olive Engineering Ltd Aircraft with cables to deploy hanging cabin
US20090146010A1 (en) * 2006-05-11 2009-06-11 Nehemia Cohen Aerial transport system
US8876057B2 (en) 2006-07-27 2014-11-04 Sikorsky Aircraft Corporation Aerodynamic integration of a payload container with a vertical take-off and landing aircraft
WO2008085547A3 (en) * 2006-07-27 2008-11-06 Sikorsky Aircraft Corp Aerodynamic integration of a payload container with a vertical take-off and landing aircraft
US20100012769A1 (en) * 2006-07-27 2010-01-21 Alber Mark R Aerodynamic integration of a payload container with a vertical take-off and landing aircraft
US20100065691A1 (en) * 2008-09-12 2010-03-18 Droney Christopher K Modular externally accessible batteries for an aircraft
US8393580B2 (en) 2008-09-12 2013-03-12 The Boeing Company Modular externally accessible batteries for an aircraft
US8511613B2 (en) * 2008-09-12 2013-08-20 The Boeing Company Modular externally accessible batteries for an aircraft
US20100178176A1 (en) * 2009-01-09 2010-07-15 Jeremy Kenyon Retractable Pump System
US20130277074A1 (en) * 2010-09-29 2013-10-24 Ramon Corujo Pardo Fire extinguishing device
US9333379B2 (en) 2012-01-27 2016-05-10 Simplex Manufacturing Co. Aerial fire suppression system
US9981150B2 (en) 2012-01-27 2018-05-29 Simplex Manufacturing Co. Aerial fire suppression system
US11439852B2 (en) 2012-01-27 2022-09-13 Simplex Manufacturing Co. Aerial fire suppression system
US10369392B2 (en) 2012-01-27 2019-08-06 Simplex Manufacturing Co. Aerial fire suppression system
WO2014171998A1 (en) * 2013-02-05 2014-10-23 Biosphere Aerospace, Llc Drone cargo helicopter
US20140217230A1 (en) * 2013-02-05 2014-08-07 Biosphere Aerospace, Llc Drone cargo helicopter
US10112810B2 (en) * 2014-02-11 2018-10-30 R. Stahl Schaltgerate Gmbh Lifting hoist with hysteresis clutch
US10450065B2 (en) 2014-12-02 2019-10-22 Amazon Technologies, Inc. Stabilized airborne drop delivery
US9688404B1 (en) * 2014-12-02 2017-06-27 Amazon Technologies, Inc. Stabilized airborne drop delivery
US20160280372A1 (en) * 2015-03-25 2016-09-29 Nolan Russell Poness Craned air transporter
US9676481B1 (en) 2015-03-27 2017-06-13 Amazon Technologies, Inc. Tether compensated airborne delivery
US10647427B2 (en) 2015-03-27 2020-05-12 Amazon Technologies, Inc. Tether compensated airborne delivery
US10406390B2 (en) 2016-08-09 2019-09-10 Simplex Manufacturing Co. Aerial fire suppression system
US11717711B2 (en) 2016-08-09 2023-08-08 Simplex Manufacturing Co. Aerial fire suppression system
US11447248B2 (en) * 2017-12-21 2022-09-20 Elroy Air, Inc. Unmanned vehicle cargo handling and carrying system
US12054260B2 (en) 2017-12-21 2024-08-06 Elroy Air, Inc. Unmanned vehicle cargo handling and carrying system
US11655031B2 (en) 2017-12-21 2023-05-23 Elroy Air, Inc. Unmanned vehicle cargo handling and carrying system
EP3774431A4 (en) * 2018-04-04 2021-12-29 Terex South Dakota, Inc. Hydraulic drivetrain for a utility vehicle
US11649049B2 (en) * 2018-06-28 2023-05-16 Justin Wesley Green Unmanned coaxial rotor aerial vehicle for transport of heavy loads
US20200331603A1 (en) * 2018-06-28 2020-10-22 Justin Wesley Green Unmanned coaxial rotor aerial vehicle for transport of heavy loads
CN111003183A (zh) * 2018-10-05 2020-04-14 极光飞行科学公司 用于自主物体拾取的地面操作
WO2020219818A1 (en) * 2019-04-24 2020-10-29 Breeze-Eastern Llc Hoist system and process for sway control
US11760486B2 (en) 2019-04-24 2023-09-19 Breeze-Eastern Llc Hoist system and process for sway control

Also Published As

Publication number Publication date
DE1815616B2 (de) 1972-09-28
BR6905495D0 (pt) 1973-04-05
DE1815616A1 (de) 1970-02-05
GB1247928A (en) 1971-09-29

Similar Documents

Publication Publication Date Title
US3510107A (en) Multiple hoist synchronization system
US2764869A (en) Means for synchronizing the travel of two or more traveling work elements
US2398421A (en) Electrohydraulic control system
US2864239A (en) Electro-hydraulic servo system for steering dirigible craft
US2695145A (en) Boost control system
US2943822A (en) Aircraft control by thrust producers
US2183932A (en) Automatic trim control for
US3847251A (en) Control apparatus for a powered hoist
US2861756A (en) Manual control system for modifying or overcoming the aircraft auto pilot control
CN113511601A (zh) 回转液压系统、工程机械及回转控制方法
US3126706A (en) Hydraulically operated- unit
US3273860A (en) Hydraulic system
US2325108A (en) Aircraft control device
US3520231A (en) Hydraulic supply systems with flow rate-limiting control
US2723089A (en) Aircraft control and indicating apparatus
US3469821A (en) Depth control system for towed body
US2315501A (en) Automatic glide and/or climb control
US2598180A (en) ken yon
US2403095A (en) Traversing hoist
US2244830A (en) Power transmission
US3606256A (en) Winch control systems
US2414473A (en) Control system for winch drives
US3556484A (en) Aerial tramway power and control means
US2967675A (en) Control system for coil support
US3458053A (en) Cable control apparatus