US3215912A - Radio controlled motor driven lifting and lowering device - Google Patents

Description

m= M ww 5 mm M N l|.||lll Z a H J N v N :m E lull 5 i J I n D m P u B I ow NMAI N lllllll I] L NW wQ\ R lllll ll m% h J. P. BRUNO Filed July 16, 1962 RADIO CONTROLLED MOTOR DRIVEN LIFTING AND LOWERING DEVICE Nov. 2, 1965 United States Patent 3,215,912 RADIO CONTROLLED MOTOR DRIVEN LIFT- ING AND LOWERING DEVICE Joseph P. Bruno, Cupertino, Calif., assignor to Opco Industries, Inc., San Jose, Calif., 21 corporation of California Filed July 16, 1962, Ser. No. 210,134 5 Claims. (Cl. 318-16) This invention relates to remote control systems, and more particularly to a remote control system for controlling the operation of raising and lowering mechanisms.

The present invention is particularly applicable to control the operation. of motor circuits for raising and/or lowering basketball backboards. Swing up type backboards have been in use for some time in gymnasiums. These backboards havebeen raised and lowered by means of cables and hand operated winches and more recently by means of electric motor operated winches. Heretofore, wherever electric motors were employed, extensive electric wiring and switches were required to provide direct electrical control to the motors. Such extensive wiring entails costly, as well as unsightly, installation of conduits, switch boxes and safety devices. Moreover, each separate backboard unit required its own circuit and system, unless lengthy wiring extended across the entire basketball court, some 75 to 90 feet distance.

The present invention contemplates the provision of an operating circuit and a motor on each swing up frame requiring only two conductive wires to supply electrical current thereto for operation by a remote control sender which may be carried on ones person. This feature contemplates the provision of a push button sender and a receiver on the swing up frame sensitive to only the signal from such sender.

Most gymnasiums of regulation size have practice backboards on opposite sides of the court in addition to the official pair or set of one at each end of the gymnasium. In most gymnasiums there are two pairs of practice sets of basketball backboards, a pair on each side and adjacent each end of the court, so that there are six in all around the boundary line of the court. Usually, the main swing up backboards, during practice sessions, are up and out of the way and are lowered for an ofiicial game. The practice backboards at the sides are raised and out of the way .during the official game.

It should also be remembered that on very many campuses, several different basketball courts may be required, some in separate buildings but close enough that electronic signals intended for one particular set of motors could and do effect and possibly operate those in other courts or buildings. The present invention has for its principal object, the provision of a remote control system for operating only one particular set of basketball backboards and no other. This object contemplates a sender transmitting a modulated signal to particular re- .usually located at opposite ends of a playing field and each separately supplied with 110 volt A.C. electrical power via a single two-Wire power line. The score keeper .holds a sender unit by which modulated signals are transmitted to the receivers within the separate scoreboards. If the modulate-d signal is the intended or predetermined signal, then the 110 volt A.C. circuits to the mechanisms to be operated are completed.

3,215,912 Patented Nov. 2, 1965 These and other objects of the present invention will become apparent from a reading of the following description in the light of the accompanying drawing in which:

FIG. 1 is a schematic diagram of the remote control system and basketball backboard embodying the present invention.

Illustrated in FIG. 1 is a swing-up type backboard 10 for a basketball court. A suitable frame 15 supports the backboard 10 for movement between its raised position and its lowered position. Connected to the backboard 10 is suitable mechanical linkage 20, which is mounted on the frame 15 and is activated by an electrical motor in a motor circuit 25 for the raising and the lowering of the backboard 10.

The operation of the electrical motor circuit 25 is cont-rolled by a receiver 30. Both the receiver 30 and the electrical circuit 25 are mounted on the frame 15. According to the present invention, the receiver 30 causes the electrical motor circuit 25 to operate only in response to the reception of an intended modulated signal having a predetermined carrier frequency and the detection of a demodulated signal of a predetermined frequency.

A transmitter or sender unit 35, which is portable so as to be conveniently carried by an operator, is activated by the actuation of a push button 40 to emit the intended modulated signal having the predetermined carrier frequency and the predetermined modulating frequency when an operator desires to lower or to raise the backboard 10. While only one backboard 10 has been shown and described, conventionally there a-re a plurality of backboards 10 for .a basketball court. Each backboard 10 will have its individual swing-up frame 15, mechanical linkage 20, electrical motor circuit 25 and receiver 30. However, the sender unit 35 may be employed to transmit the intended modulated signal to more than one receiver 30 for the raising and the lowering of a plurality of backboards 10 in unison.

As shown in FIG. 1, the portable transmitter 35 comprises a single stage 41, which functions as a high frequency oscillator to produce the carrier frequency signal, a low frequency oscillator to produce a modulating frequency signal, and a modulator to produce the modulated signal. In the preferred embodiment of the present invention, the frequency of the carrier signal is 50 megacycles and the frequency of the modulating signal is 120 kilocycles.

The single stage 41 includes a suitable subminiature electron transmitting tube 42, such as CK5676 tube, having a heated cathode 43, a control grid 44 and a plate 45. Plate voltage of preferably volts is continuously applied to the plate 45 over the following path: ground, battery 46, transformer 47, inductance coil 48 and the plate 45 of the electron tube 42.

A plate circuit 50 of the transmitter 35 is tuned to resonate at the carrier frequency and comprises an antenna 51 and a trimmer capacitor 52. By adjusting the trimmer capacitor 52, the plate circuit 50 is tuned to resonate at the predetermined carrier frequency. A

coupling capacitor 53 blocks the DC. plate voltage from being applied to the control grid 44 and couples the feedback of the resonating high frequency signal from the output of the plate circuit 50 to the control grid 44 to produce high frequency oscillations at the predetermined carrier frequency. The inductance coil 48 is located between the output circuit 50 and the transformer 47 to offer a high impedance to the carrier frequency signal.

In series with the inductance coil 48 and the battery 46 is the primary winding of the transformer 47. The secondary Winding of the transformer 47 forms a tuned circuit 54 with capacitors 55 and 56 to resonate at the low frequency or the predetermined modulating frequency. The tuned circuit 54 is coupled to the control grid 44 through a capacitor 60, grid resistor 61 and a grid biasing resistor 62. By adjusting the tuning slug of the transformer 47, the circuit 54 is tuned to resonate at the predetermined modulating frequency.

The primary winding of the transformer 47 is excited by the low frequency current flow in the plate circuit 50 to feed back low frequency signals to the tuned grid circuit 54 to produce low frequency oscillations at the predetermined modulating frequency. By applying the modulating low frequency signal to the grid 44, the stage 41 is grid modulated to produce in the output circuit 50 a modulated signal having the predetermined carrier fre quency signal modulated by the predetermined low frequency modulating signal.

Thus, while the tube 42 is conducting, the antenna 51 transmits a modulated signal having a preselected carrier frequency and a preselected modulating frequency.

For controlling the conduction of the electron tube 42, the push button 40 interconnects a suitable source of filament heating power, such as battery 65, to the filament cathode 43 of the tube 42. The electron transmitting tube 42 employs an instant-type heating filament. Hence, when the push button 40 is not actuated, the tube 42 does not conduct and there is no drain on the battery 46. When the push button 40 is actuated, the filament heating circuit is closed to connect the battery 65 to the filament cathode 43, whereby the tube 42 conducts and the antenna 51 transmits the preselected modulated signal.

The receiver 30 comprises a suitable receiving antenna 68, which receives the intended modulated signal emitted by the transmitter 35. The antenna 68 has a low input impedance and is resistance loaded by a resistor 69 to reduce the possibility of self-oscillation, to reduce sensitivity to outside interference and to effect maximum transfer of energy.

The modulated signal received by the antenna 68 is fed to a tuned amplifier 70, which comprises a triode vacuum tube 71 having a cathode 72, a control grid 73 and a plate 74. Connected to the cathode 72 is a parallel resonant circuit 75, which comprises a capacitor 76 and an inductance coil 77. The resonant circuit 75, which has a narrow band, resonates substantially at the predetermined or preselected carrier frequency, which in the preferred embodiment is 50 megacycles.

Connected to the control grid 73 is a grid resistor 78 and a fixed potential biasing network 79 having .a resistor 80 and a source of direct current potential, such as a battery. The tube 71 is biased to cut-off by the biasing network 79. The modulated signal fed to the amplifier 70 is impressed across the cathode resonant circuit 75.

If the incoming signal is of a frequency substantially of the predetermined carrier frequency or the intended carrier frequency, the resonant circuit 75 has a high impedance or reactance and a sufficient signal is produced to overcome the fixed bias on the control grid 73, whereby the tube 71 conducts. In case the incoming modulated signal is not of a frequency substantially of the intended signal or does not include a carrier frequency substantially of the predetermined carrier frequency, the voltage applied to the cathode 72 would be insufficient to overcome the fixed bias on the grid 73 and the tube 71 will not conduct.

Connected to the plate 74 of the tube 71 is a highly selective or narrow band tuned parallel resonant output circuit 83 having a trimmer capacitor 84 and an inductance coil 85. The output circuit 83 is tuned to resonate at the predetermined or preselected carrier frequency, which in the preferred embodiment is 50 megacycles. Plate voltage is applied to the plate 74 of the tube 71 over the following pathz' power supply 86, resistor-capacitor network 87 and inductance coil 88.

From the foregoing, it is to be observed that the tuned amplifier 70 produces an amplified output signal only when the incoming signal from the antenna 68 is the predetermined carrier frequency or the intended carrier signal. Other signals are thereby rejected and are not amplified.

The amplified incoming signal having the predetermined carrier frequency is then fed to a demodulating stage 90 having an NPN transistor 91, such as a 2N35 or 2N169. The stage 90 is in the nature of a commonemitter transistor detector and the transistor 91 comprises a base 92, an emitter 93 and a collector 94.

A blocking capacitor 95 couples the amplified incoming signal of the predetermined carrier frequency to the base-emitter circuit of the transistor 91 for demodulation over the following path: base 92, resistor 95, resistor 96, ground, and emitter 93. The demodulated signal is produced across a load resistor 97 over the following path: collector 94, load resistor 97, resistor 89, power supply 86, ground and emitter 93.

The demodulated signal produced across the load resistor 97 is coupled to a low frequency amplifier 98 by way of a blocking capacitor 99. Included in the low frequency amplifier 98 is an electron triode tube 100, such as one-half of a 12AZ7 tube, which includes a cathode 101, control grid 102 and a plate 103. The demodulated signal is impressed on the control grid 102 through a grid resistor 104.

A fixed bias is provided for the amplifier 98 by means of a storage capacitor 105 that is charged over the following path: ground, capacitor 105, resistor 89, capacitor 106 of the power supply 86, and ground. The fixed DC potential across the capacitor 105 is applied to the amplifier 100 for biasing the same over the following path: ground, capacitor 105, resistor 107, cathode 101 of the tube 100, cathode resistor 108 and ground. Hence, a positive potential is impressed on the cathode 101 to bias the tube 100. Connected to the plate 103 of the tube 100 is the primary winding of an output transformer 109 and a relay 110 having normally open contacts 111. In parallel with the coil of the relay 110 is a capacitor 112 for reducing arcing and dissipating induction surges of voltage that may be created.

When the demodulated signal is impressed on the control grid 102 of the tube 100, the tube 100 conducts and an amplified signal is produced across the output transformer 109. At this time, the relay 110 in the plate circuit of the low frequency amplifier 98 does not operate, since the current flow through the coil thereof is insutficient to fully energize the same.

The amplified demodulated signal produced across thesecondary winding of the transformer 109 is transmitted to a parallel resonant circuit 115 having an inductance coil 116 and a capacitor 117. The resonant circuit 115 is tuned to the preselected low frequency or the intended modulating frequency, which in the preferred embodiment is kilocycles. It is to be observed that the resonating circuit 115 is highly selective and of a narrow band and, thus, passes or presents a high impedance only to the intended low frequency signal. The resonating circuit 115 receives the incoming signal over the following path: secondary winding of trans? former 109, resonating circuit 115, resistor 118 and back to the secondary winding of the transformer 109.

After the amplified low frequency signal advances from the resonating circuit 115, it is rectified by a rectifying circuit 120. The rectifying circuit 120 includes suitable silicon diodes 121 and 122. Interconnecting the diodes 121 and 122 are filter circuits 123 comprising resistor 124, capacitor 125, resistor 126 and capacitor 127. The rectified output signal from the rectifying circuit 120 charges a storage capacitor 130 by way of a resistor 131. The positive potential charge on the capacitor 130 is impressed on the control grid 102 of the low frequency amplifier 98 through .a' resistor 132.

If the demodulated signal impressed across the resonant circuit 115 is the intended signal or the predetermined tation of the motor.

frequency amplifier 18, whereby sufficient current will flow in the plate circuit thereof to operate the relay 110.

On the other hand, if the signal impressed across the resonant circuit 115 is not the intended signal or the predetermined modulating frequency sign-al, then the magnitude of the charge on the storage capacitor 130 is insufficient to reduce the fixed bias on the low frequency amplifier 98 to the point that the tube 100 will conduct enough current to operate the relay 110.

The electrical motor circuit 25, which operates the backlboard lifting and lowering linkage 20, comprises a suit able transformer 140 having the primary thereof connected to a suitable source of electrical energy, such as gized to contact successive ratchet contacts 144-147.

Alternate contacts 144, 146, 141' and 146' are dead so that no circuit is completed through them. Contacts 145,

146, .145, 146' when contacted by the wiper 143 complete the motor circuit 25 to energize the motor M. 'The motor M is a reversible motor which automatically reverses itself each time it is energized.

Initially, the wiper 143 rests on a dead contact 144, 146, 144' or 146. When the relay 110 is operated, contacts 111 are closed to energize the stepping coil 141, a pawl 149 operates the ratchet 150 whereby the wiper 143 is moved to rest on a hot contact, for example 145. Each subsequent operation of the relay 110 results in .successive step-by-step movement of the wiper 143 to stop I and start the motor M.

The wiper 143 is like a switch in the motor circuit 25 in that :it is connected to one side of the source of alternating 115 v. current power. The other side. of the source of alternating current power is connected directly to the reversible motor M. One winding'of the motor M is connected to the contact 145 via a motor plate 151 for operating the motor in one direction. The other winding of the motor M is connected to the contact 147 via the motor plate 151 for reversing the direction of ro- When the wiper 143 rests on either contact 145 or 145', the motor 150 is energized to turn its shaft in one direction and when the wiper 143 rests on either contact 147 or 147', the direction of rotation of the motor shaft is reversed.

The shaft of the motor M imparts rotary movement to the shaft of a winch drum 152 in a conventional and well-known manner. When the direction of rotation of the motor shaft is reversed, the direction of rotation of the shaft of the winch drum 152 is reversed. Trained around the drum 152 is a cable 153 having the free end thereof attached to a pivotal link 154 of the swing-up frame 15. The swing-up frame 15 comprises a fixed platform 155 that is fixedly secured to a part of a building B. Mounted on the platform 155 are the receiver 30, the electrical motor M and motor circuit 25 and the mechanical linkage 20.

At One end thereof, the link 154 is pivotally attached Y in the down position, which is the position shown in solid lines. By advancing the wiper 143 to rest on contact 145,

the motor M is operated to rotate the shaft thereof in a direction whereby the drum 152 winds the cable 153 therearound to move the backboard 10 upwardly. When the backboard 10 reaches the position shown in dashed lines, a limit switch 159 is contacted by the link 154 and actuated to complete circuit to a coil 160 on the step up mechanism 142 to advance the wiper 143 to dead contact 146 and thereby stop the motor M to prepare the down energizing circuit of the motor M for operation.

The next time the push button 40 of the sender 35 is operated, the signal transmitted to the receiver 30 will again energize the coil of relay to advance the ratchet 150 and wiper 143 one step. By stepping the wiper 143 to the contact 147, the motor M is operated to rotate its shaft in a reversed direction, whereby the drum 152 unwinds the cable 153, thereby enabling the backboard 10 to once again assume its lowered position. When the backboard 10 reaches the position shown in solid lines, a limit swtich 161 is actuated to again energize the coil 160 to move the wiper 143 off live contact 147 and onto dead contact 144. The device is thus ready for the next cycle of operation when the push button 40 of the transmitter 35 is again operated.

In the operation of the remote control system of the present invention, it is assumed that the backboard 10 is in the down position (shown in solid line) and the wiper 143 of the ratchet switch 142 is resting on the contact 144. If an operator desires to raise the backboard 10 to the position shown in dashed line, he actuates the push button 40 \of the transmitter 35 for a short time interval and then releases the same. Thereupon, the transmitting tube 42 conducts and the antenna 51 transmits a modulating signal having the predetermined carrier frequency and the predetermined modulating frequency.

The modulated signal transmitted by the sending unit 35 is received by the antenna 68 of the receiver 30 and fed to the tuned amplifier 70. If the signal received by the tuned amplifier 70 is not the predetermined frequency of theintended carrier, the signal will be rejected. On the other hand, if the signal received by the tuned amplifier is the predetermined signal of the intended carrier, then the signal will be amplified and passed to the demodulating stage 90, which produces the low frequency signal or the demodulated signal.

The demodulated signal is then amplified by the low frequency amplifier 98. The low frequency amplifier 98 has a fixed biasing potential thereon so that the tube 100 thereof normally does not produce a sufficient plate current to operate the relay 110. After the demodulated signal is amplified by the low frequency amplifier 98, it is fed to the resonant circuit 115. The resonant circuit or overcome the fixed bias on the low frequency amplifier 98, whereby sufiicient current will flow in the plate current thereof to operate the relay 110.

On the other hand, if the demodulated signal impressed across the resonant circuit 115 is not the intended signal or the predetermined low frequency signal, then the magnitude of the charge on the storage capacitor is insufficient to reduce or overcome the fixed bias on the low frequency amplifier to the point that thetube 100 will contlilligt a current of sulficient magnitude to operate the relay When the relay 110 is operated, contacts 111 close to energize the stepping coil 141 of the switch 142. This result thereof, the motor M is operated to rotate the shaft thereof in the direction for rotating the drum 152 for raising the backboard 10. At the time the backboard 10 asshort time interval.

sumes the position shown in dashed line, the limit switch If the operator desires to lower the backboard 10 to .the position shown in'solid lines, the operator again actuates the push button 40 of the transmitter 35 for a short time interval. The transmitter 35 and the receiver 30 operate in the same manner previously described. When relay 110 closes contacts 111, the stepping coil 141 is energized to move the wiper 143 to the contacts 147 of the switch 142. Since the push button 40 is closed for a short time interval, the relay 110 will be operated for only a When the relay 110 is deenergized, the contacts 111 will return to their normally open position.

- Theengaging of the wiper 143 with the contacts 147 completes the down" circuit for the motor M. As a consequence thereof, the motor shaft rotates in a reversed direction to rotate the drum 152 in a direction whereby the cable 153 enables the backboard 10 to be lowered. When the backboard 10 reaches the lowered position (shown in solid lines) the limit switch 161 energizes the coil 160 of the step up mechanism 142 and interrupts the down motor circuit and prepares the up motor circuit for operation.

It should here be noted that should the operator change his mind or for any reason, should it be desirable or necessary to 'stop the up or down movement of the backboard 10, he need only press the push button 40 which would automatically energize the coil of relay 110 to close switch 111 and thereby energize coil 141 to advance the ratchet and wiper 143 to a dead contact and thereby stop the motor M.

It is to be understood that modifications and variations of the embodiment of the invention disclosed herein may be resorted to without departing from the spirit of the invention and the scope of the appended claims.

Having thus described my invention, What I claim as new and desire to protect by Letters Patent is:

1. A remote control system for controlling the operation of a lifting and lowering device comprising selective signal receiving means for receiving a modulated signal and for passing a modulated signal of a predetermined carrier frequency, a demodulator connected to said signal receiving means for demodulating said passing modulated signal of said predetermined carrier frequency to produce a lower frequency signal, an amplifier for amplifying said lower frequency signal, a first capacitor for applying a fixed biasing potential to said amplifier, means for charging said first capacitor to said fixed biasing potential, a second capacitor coupled to said amplifier for receiving the amplified frequency signal and for reducing the effective biasing potential on said amplifier in response to said lower frequency signal being of a predetermined frequency, and means connected to said amplifier and activated in response to said amplifier having the effective biasing potential thereon reduced for actuating said lifting and lowering device.

2. A remote control system for controlling the operation of a lifting and lowering device comprising selective signal receiving means for receiving a modulated signal and for. passing a modulated signal of a predetermined carrier frequency, a demodulator connected to said receiving means for demodulating said passing modulated signal of said predetermined carrier frequency to produce a lower 1 frequency signal, an amplifier for amplifying said lower frequency signal, a first capacitor for applying a fixed biasing potential to said amplifier, means for charging said first capacitor to said fixed biasing potential, a second capacitor coupled to said amplifier for receiving the amplified low frequency signal and for reducing the effective biasing potential on said amplifier in response to said lower frequency signal being of a predetermined frequency, a

I relay connected to said amplifier and operative in response to said amplifier having the effective biasing potential for passing a modulated signal of a predetermined carrier frequency, a demodulator connected to said signal receiving means for demodulating said passing modulated signal of said predetermined carrier frequency to produce a lower frequency signal, an amplifier for amplifying said lower frequency signal, a first capacitor for applying a fixed biasing potential to said amplifier, means for charging said first capacitor to said fixed biasing potential, a second capacitor coupled to said amplifier for receiving the amplified lower frequency signal and for reducing the effective biasing potential on said amplifier in response to said lower frequency signal being of a predetermined frequency, a relay connected to said amplifier and operated in re sponse to said amplifier having the effective biasing potential thereon reduced, a step-by-step switch actuated in response to each operation of said relay for successively advancing the wipers thereof, and motor means connected to said switch and responsive to the location of said wiper for at times actuating said device to effect a lifting operation and at other times actuating said device to effect a lowering operation.

4. A remote control system for controlling the operation of a device comprising selective signal receiving means for receiving a modulated signal and for passing a modulated signal of a predetermined carrier frequency, a demodulator connected to said signal receiving means for demodulating said passing modulated signal of said 'means connected to said amplifier and activated in response to said amplifier having the effective biasing potential thereon reduced for activating said device.

5. A remote control system for controlling the opera tion of a device comprising selective signal receiving means for receiving a modulated signal and for passing a modulated signal of a predetermined carrier frequency, a demodulator connected to said receiving means for demodulating said passing modulated signal of said predetermined carrier frequency to produce a lower frequency signal, an amplifier for amplifying said lower frequency signal, a first capacitor for applying a fixed biasing potential to said amplifier, means for charging said first capacitor to said fixed biasing potential, a second capacitor coupled to said amplifier for receiving the amplified low frequency signal and for reducing the effective biasing potential on said amplifier in response to said low frequency signal being of a predetermined frequency, a relay connected to said amplifier and operative in response to said amplifier having the effective biasingpotential thereon reduced, and means activated in response to the operation of said relay for activating said device.

References Cited by the Examiner UNITED STATES PATENTS 2,474,527 6/49 Heisner 3l8-16 2,509,345 5/50 Howell et al 318460 X 2,865,634 12/58 Townsend 2731.5 2,992,378 7/61 Schneider 318-16 3,002,140 9/61 Banner 31816 3,076,935 2/63 Jones 318-16 X ORIS L. RADER, Primary Examiner.

Claims (1)

1. A REMOTE CONTROL SYSTEM FOR CONTROLLING THE OPERATION OF A LIFTING AND LOWERING DEVICE COMPRISING SELECTIVE SIGNAL RECEIVING MEANS FOR RECEIVING A MODULATED SIGNAL AND FOR PASSING A MODULATED SIGNAL OF A PREDETERMINED CARRIER FREQUENCY, A DEMODULATOR CONNECTED TO SAID SIGNAL RECEIVING MEANS FOR DEMODULATING SAID PASSING MODULATED SIGNAL OF SAID PREDETERMINED CARRIER FREQUENCY TO PRODUCE A LOWER OF FREQUENCY SIGNAL, AN AMPLIFIER FOR AMPLIFYING SAID LOWER FREQUENCY SIGNAL, A FIRST CAPACITOR FOR APPLYING A FIXED BIASING POTENTIAL TO SAID AMPLIFIER, MEANS FOR CHARGING SAID FIRST CAPACITOR TO SAID FIXED BIASING POTENTIAL, A SECOND CAPACITOR COUPLED TO SAID AMPLIFIER FOR RECEIVING THE AMPLIFIED FREQUENCY SIGNAL AND FOR REDUCING THE EFFECTIVE BIASING POTENTIAL ON SAID AMPLIFIER IN RESPONSE TO SAID LOWER FREQUENCY SIGNAL BEING OF A PREDETERMINED FREQUENCY, AND MEANS CONNECTED TO SAID AMPLIFIER AND ACTIVATED IN RESPONSE TO SAID AMPLIFIER HAVING THE EFFECTIVE BIASING POTENTIAL THEREON REDUCED FOR ACTUATING SAID LIFTING AND LOWER DEVICE.

Images