Gravity operated electromagnetically controlled gate
United States Patent McDonald [4 1 Apr. 15, 1975 GRAVITY OPERATED ELECTROMAGNETICALLY CONTROLLED GATE lnventor: Robert R. McDonald, 6028 Moss Bank Dr., Palos Verdes Pennisula, Calif. 90274 22] Filed: Mar. 18, 1974 [21] Appl. No.: 451,950  
 [52] US. Cl. 49/334; 49/139; 49/280; 49/335; 49/379 [51] Int. Cl. E0lf 13/00; E05f l/OO; E05f 15/10 [58] Field of Search 49/324, 35, 334, 49, 349, 49/124, 327, 335, 139, 379, 280; 246/125, 128  
 [56] Reference? Cited UNITED STATES PATENTS 599,020 2/1898 Small 49/280 X 903,905 11/1908 Smith 49/280 X 1,601,783 10/1926 Wallin 49/280 1,612,016 12/1926 Harper 49/335 1,663,040 3/1928 Duchshercr..... 49/280 X 1,765,178 6/1930 Rick 49/280 X 3,368,305 2/1968 Pickarski 49/35 X Primary ExaminerPhilip C. Kannan Attorney, Agent, or Firm-George F. Smyth I ix [57] ABSTRACT An electromagnetically controlled, gravity operated gate of simple construction and of reliable performance includes a housing enclosing the principal functional components of the gate assembly. Extending through a wall of the housing is a drive shaft on which is mounted a gate element, the latter including a counterbalanced channel affixed to be rotated by the drive shaft, the channel having affixed thereto a gate arm. Located within the housing is a motor and clutch assembly connected to drive the gear means to which the drive shaft is affixed. Also cooperating with the drive shaft is a follower arm which cooperates with an electromagnet positioned within the housing to maintain the gate arm in a generally horizontal position. Also located within the housing is a switch engageable by the follower arm to maintain the electromagnet energized while the gate is in the horizontal position. A control circuit is provided which in an energized state activates the motor and clutch assembly for moving the gate arm from a vertical to a horizontal position, the switch means being energized by the follower to de-energize the motor, to maintain the electromagnet energized for maintaining the gate arm in the horizontal position. Movement of the gate from the horizontal to the vertical position is achieved by de-energizing the circuit control means so that the gate arm is moved to the vertical position by gravity.  
 10 Claims, 5 Drawing Figures PATENTEBAPR 1 5 SHEET 1 OF 2 GRAVITY OPERATED ELECTROMAGNETICALLY CONTROLLED GATE BACKGROUND OF THE INVENTION Automatically controlled gate assemblies are known in the prior art, particularly the gate assemblies used at railway crossings, the gate assemblies being complex in structure and operated by signals received by an advancing train.  
  More recently, gate assemblies have been used in automotive parking lots and are raised once a parking receipt is removed from a dispensing machine. Another variety of gate is that used in private parking lots, usually in conjunction with a coded card which is recognized electronically and actuates a mechanism permitting the gate to be raised.  
  In other instances. a gate is used for control of traffic on private access roads. the gate being energized by a control mechanism located in the security office normally positioned in close proximity to the access road.  
  Heretofore, gate assemblies have been constructed to operate in a variety of different ways, including an energizing circuit which affirmatively controls movement of the gate from the horizontal to the vertical position and from the vertical position to the horizontal. This type of arrangement is sometimes objectionable because of problems associated with a power failure or malfunction of the gate or its control apparatus. For example, if a gate is positively driven through its various positions, and is in the vertical position, a malfunction or loss of power results in the gate being maintained in a horizontal position thus obstructing the controlled flow oftraffic. In high density traffic areas such as parking lots or private access roads, this is objectionable.  
  Other gates have been designed and operated which are somewhat complex and require highly trained individuals in order to repair or to perform routine maintenance on the gate assemblies. Some of these structures have been designed to operate on a gravity basis, that is, the gate is moved from the vertical to the horizontal position by virtue ofa counterbalanced gate arm which is caused to rotate to the horizontal position by gravity.  
  For examples of various gate structures and control assemblies, reference is made to US. Pat. No. 599.020 of Feb. I5, 1898; US. Pat. No. 903.905 of Nov. 17, 1908; US. Pat. No. 1,601,783 of Oct. 5, I926; US. Pat. No. 1,663,040 of Mar. 20, I928 and US. Pat. No. 1,765,178 of June 17, I930.  
 SUMMARY OF THE INVENTION The present invention relates to a gate assembly and more particularly to an improved gate assembly which is electromagnetically controlled and gravity operated by a simpleand reliable assembly whose principal functional components are enclosed within a single housing. By the present invention, several of the disadvantages of prior art gate assemblies have been overcome, the principal advantage of the present invention being the simplicity of the structure and its effectiveness as a controllable gate assembly. Thus, a counterbalanced gate element is used which is rotated from the horizontal to the vertical position by gravity, and driven from the vertical to the horizontal position by a motor, clutch and gear assembly. Thus, in the event of a power failure, the gate automatically raises to the vertical position and does not act as a traffic obstruction barrier.  
 Additionally, because of the simplicity of the structure it is possible, in the event of some mechanical malfunction, manually to raise the gate to the vertical position thus permitting flow of traffic.  
  The highly reliable and effective gate structure of the present invention is enclosed within a housing, thus making it ideal for outdoor use. Positioned within the housing are the major functional components of the gate assembly and its driving mechanism, the latter including a motor and clutch assembly, the output of the clutch being a gear assembly which effects rotation of a gate arm. Attached to rotate within the housing as the gate arm rotates is a follower arm which contacts a brake and shock absorber assembly as the gate is rotated from the horizontal to the vertical position, and which is engaged by an electromagnet to maintain the gate in the horizontal position. As the gate arm is rotated towards the horizontal position from a vertical position, the follower actuates a switch which deenergizes the motor but maintains an electromagnet energized to hold the follower arm and thus the gate.  
  To raise the gate, the control circuit is de-energized which affects release of the electromagnet and gravity causes the gate to rotate from the horizontal to the vertical position as described. The gate element itself includes a channel member mounted to be rotated by the drive shaft which is affixed to the gear assembly, the channel member carrying a gate arm which is at an angular orientation with respect to the channel member, the channel member being counterbalanced such that the counterweight tends to rotate the gate towards the vertical position from a horizontal position. The present invention can best be understood by reference to the following description taken in connection with the accompanying illustrative drawings.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in perspective of the gate assembly of the present invention;  
  FIG. 2 is a view partly in section and partly in elevation of the interior components of the gate assembly in accordance with the present invention;  
  FIG. 3 is a view, partly in section and partly in elevation of the shock absorber assembly in accordance with the present invention;  
  FIG. 4 is a view, in perspective, of the interior working components of the gate assembly in accordance with the present invention; and  
  FIG. 5 is a plan view which also shows the electrical control apparatus of the gate assembly in accordance with the present invention.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings which illustrate a preferred embodiment of the present invention, FIG. 1 shows the gate assembly 10 which includes a lower support member and housing 11 above which is received an upper housing member 12 such that substantially all of the interior working mechanism of the gate assembly is completely closed and protected from the outside environment.  
  Extending through the housing 12 is a drive shaft 15 on which is mounted a gate element 20 including a channel member 21 and a gate arm 22, the latter affixed to the channel member 21. As illustrated, the channel member 21 carries a weight 24 whose position may be adjusted by sliding it along the channel member and securing it in place a proper distance from the drive shaft so as to effect a change in the rate at which the gate arm rotates from the horizontal to the vertical position. Normally, the weight 24 is adjusted to overcome the inertia of the gate arm allowing gravitational forces to raise the gate arm from the horizontal position, indicated in phantom lines, to the vertical position. The rate of movement from the horizontal to the vertical position is controlled by the adjustment of the position of the counterbalance weight 24, as described. Also mounted exteriorally of the housing 12 is a shock absorber assembly 26 which is contacted by the underside of the gate arm 22 as the latter is positively driven from the vertical position to the horizontal position.  
  Referring to FIG. 3, the details of the shock absorber 26 are shown, the shock absorber including a hollow aluminum spindle 27 affixed on a support member generally indicated 28, the interior of the spindle including a spring 29 on which is mounted a Teflon cup 30 the latter being slidable with respect to the spindle 27.  
  Referring to FIGS. 2 and 4, the interior working components of the gate assembly include a motor mounted on a platform 36 supported between the frame members 37 and 38, the latter attached to the vertically extending frame members 39 which are affixed to a suitable base which may be a wood or concrete foundation. The output shaft 42 of the motor is connected to an electromagnetic clutch assembly 45 through a coupling 46 to a small spur gear 47. By way ofexample, the motor 35 and associated speed reducer may be of 1 15 volt, 30 amp, 60 cycle, l/th hp motor operating at I725 rpm. The torque generated is 32 lb. in. The clutch assembly 45 may be of a type which is a rated 9 watt dc. voltage controlled clutch having a torque of 43 lb. in.  
  As illustrated in FIGS. 2 and 4, the output shaft 49 of the coupling 46 is supported by a vertically extending frame member 50 cooperating with a vertically extending frame member 52 such that the spur gear 47 is held in fixed alignment with a larger spur gear 55 positioned vertically below it and supported between the frame members 50 and 52. The spur gear 55 is splined to the drive shaft 15 on which the gate element 20 is mounted.  
  Interiorally of the housing there is also mounted on the drive shaft a follower arm which rotates with the drive shaft 15 and the gate arm. As illustrated in FIG. 4, the follower arm 60 carries a steel plate 63 and a brake shoe 64, the steel plate cooperating with an electromagnet 65 supported on the underside of the platform 36.  
  Supported beneath the lower frame member 38 is a second shock absorber 68 of a structure identical to that already described in connection with FIG. 3. Mounted on another transverse support member 69 is a brake shoe 70 which cooperates with the brake shoe 64 carried by the follower arm 60.  
  The brake shoe 70 is relatively simple in structure and is in the form ofa brush with stiff bristles cooperating with the brake shoe 64 carried by the follower arm 60. Thus, as the gate arm moves from the horizontal to the vertical position, the brake shoe 64 comes in contact with the brake shoe 70, and the follower arm contacts the shock absorber 68 to retard the movement of the gate arm from the horizontal to the vertical. Such a feature of the present invention is of practical importance in view of the fact that movement of the gate arm from the horizontal to the vertical is-by gravitational force rather than through a positive drive through the motor and clutch assembly.  
  The gate arm will remain in the vertical or up position for as long as the circuit is not actuated. Upon actuation of the circuit, the motor is energized and the gate is positively driven from the vertical to the horizontal position.  
  As the follower arm 60 rotates with the gate arm, the plate 63 cooperates with an electromagnet 65 to maintain the gate in the horizontal position. As the follower arm 60 rotates to the horizontal position, the plate also contacts a microswitch 72 which functions to deenergize the motor and clutch assembly while main taining the electromagnet 65 energized to hold the gate in the horizontal position. As can be understood, the amount of electrical energy necessary to maintain the electromagnet energized is rather minimal, and accordingly, an effective means is provided for maintaining the gate in a horizontal position. In the event of a mechanical failure or electrical failure, the gate can be raised to the vertical position manually.  
  In movement of the gate arm from the vertical to the horizontal position, the underside of the gate arm contacts the shock absorber 26 so as to reduce any bouncing movement as the gate approaches the horizontal position thus enabling the electromagnet 65 to hold the plate 63 and the follower arm and the gate arm in a generally horizontal position.  
  Referring to FIG. 5 wherein like reference numerals have been used where applicable, electrical power is supplied through any a.c. source 75, the electrical circuit being controlled by a switch 76 which is illustrated as a manually operated switch. It is to be understood, however, that switch 76 may be operated by a ticket dispensing machine or by a card recognition circuit, in a manner well known to those skilled in the art.  
  The circuit includes a dc. converter 78 used to provide the dc. power for the electromagnetic clutch 45. Cooperating with the motor 35 is a starting capacitor 79 which functions in the usual manner of capacitance started motors. As illustrated, relay 72 is interconnected between the motor and the electromagnet 65 so as to maintain the electromagnet energized while deenergizing the motor upon actuation of the relay 72 by the plate 63 carried on the follower 60.  
  To illustrate the simplicity of the gate assembly of the present invention, the motor may be of the Bodine type N-lRG&#34; gear motor. The clutch assembly 45 may be of a Stearns style MSR electromagnetic clutch while the coupling 46 is a /2 in. X V2 in. FCS coupling. Gear 47 is a l in. diameter spur gear while gear 55 is a 9 in. diameter spur gear. The electromagnet 65 includes a dc. rectifier as part of its structure, the electromagnet being interconnected to the dc. converter 78 as illustrated in FIG. 5.  
  The gate arm is preferably of wood, metal or plastic. and mounted on the channel member 21. As illustrated in FIG. I, the gate arm 22 is offset approximately 10 with respect to the channel member 21 such that with the gate in the horizontal position, the channel member is offset in the direction of pivotal or rotational movement of the gate element. In this way, the weight 24 is positioned above the horizontal arrangement of the gate arm. and once the electromagnet is de-energized by de-energizing the circuit, gravitational forces act immediately to raise the gate from the horizontal to the vertical position. The angular disposition of the channel member with the gate arm thus assists in overcoming the inertia tending to maintain the gate arm in the horizontal position.  
  As will be apparent to those skilled in the art. the rate at which the gate moves from the horizontal to the vertical position may be adjusted by sliding adjustment of the weight 24 within the channel member 21.  
  One of the features of the present invention is the function of the shock assemblies 26 and 68 which in addition to absorbing the shock of movement of the follower arm also operates to provide an initial movement of the gate arm as it moves from the horizontal to the vertical position and as it moves from the vertical to the horizontal position. This is apparent by virtue of the spring member which is compressed slightly once the respective shock members are contacted either by the gate arm or by the follower arm.  
  it will be apparent to those skilled in the art that various changes and modifications may be made with respect to the structure herein described without departing from the scope of the invention as set forth in the appended claims.  
 I claim:  
  1. An electromechanically controlled, gravity operated gate assembly comprising:  
 an enclosed housing containing an electromechanical assembly for effecting movement of a gate arm positioned externally of said housing,  
 gear means contained within said housing and connected to a drive shaft which extends through said housing,  
 a gate element mounted on the extending portion of said drive shaft.  
 said gate element including a counterbalanced channel member affixed for movement with said drive shaft and a gate arm secured to said channel memher.  
 a motor and clutch assembly supported within said housing and connected to drive said gear means,  
 a follower arm mounted within said housing for rotation with said shaft.  
 electromagnetic means supported within said housing and cooperating with said follower arm to maintain said gate in a generally horizontal position,  
 switch means supported within said housing and engageable by said follower arm to maintain said electromagnet energized while said gate arm is in said horizontal position,  
 circuit control means operative in an energized state to activate said motor and clutch assembly for moving the gate arm from a vertical position to a horizontal position.  
 said switch means being energized in response to contact by said follower arm to de-energize said motor and clutch assembly and to maintain said electromagnetic means energized to maintain said gate arm in said horizontal position, and  
 said circuit control means in the de-energized state being operative to de-energize said switch means whereby said gate arm is moved to the vertical position by gravity.  
 2. A gate assembly as set forth in claim 1 wherein said switch means is mounted such that said motor and clutch assembly is de-energized as said follower arm contacts said switch.  
 3. A gate assembly as set forth in claim 1 wherein a shock assembly is mounted within said housing to contact said follower as said gate arm is raised to the vertical position.  
 4. A gate assembly as set forth in claim 1 wherein said gate arm is offset about 10 with respect to said channel member such that with the gate arm in the horizontal position the channel member is offset in the direction of pivotal movement of said gate ele ment.  
 5. A gate assembly as set forth in claim 1 wherein said channel member is positioned at an angle above the vertical with the gate arm in the vertical position.  
 6. A gate assembly as set forth in claim 1 wherein a resilient shock member is mounted outside of said housing for contact by said gate arm as the latter approaches the horizontal position.  
 7. A gate assembly as set forth in claim 6 wherein said shock member urges said gate arm from the horizontal position towards said vertical position in response to de-energization of said electromagnet means.  
  8. A gate assembly as set forth in claim 3 further including friction brake means mounted within said housing and cooperating with said follower arm to slow movement of said gate arm as the latter approaches the vertical position.  
 9. A gate assembly as set forth in claim 8 wherein a resilient shock member is mounted outside of said housing for contact by said gate arm as the latter approaches the horizontal position.  
 10. A gate assembly as set forth in claim 9 wherein said shock member urges said gate arm from the horizontal position towards said vertical position in response to de-en&#39;ergization of said electromagnet