US1764885A - Control system for elevators - Google Patents

Description

Jane 17,1930.

A. PINTO CONTROL SYSTEM FOR ELEVATORS original Filed ont. 6, 1925 2 Sheets-Sheet 1 www.

June 17, 1930., A. PINTO 1,764,885

CONTROL' SYSTEM FOR ELEvAToRs Original Filed Oct. 6l 1925 2 -Sheets-Sheet 2 VOLT/16E w l MPERE V5 TURNS F/g I A www @A12- ywemtoz `Patented June 17, 1930 l UNITED STATES 1 PATENT OFFICE ANTHONY PINTO, or NEW YORK. N. Y., AssIGNOR'TO o'rrs ELEvATOR COMPANY, OE

JERSEY CITY. NEW JERSEY, A CORPORATION or NEW JERSEY CONTROL SYSTEM FOB ELEVATORS Application filed October 6, 192.5, Serial No. 60,769. Renewed December 18, 1929.

The invention relates to control systems and particularly to control systems for elevators.

In elevator' control systems where the elevator motor is supplied with current by a va- 5 riablc voltage generator, the generator is required to operate over a wide range of E. M. F. values varying from a maximum in one direction to a maximum in the other. Where self-leveling apparatus is employed, the generator is required to operate at low values of E. M. F. in bringing the car to a level with a desired landing. Due to the hysteresis of the iron of the generator field, the E. M. F. values obtained for a given value of field current during leveling operation vary considerably, depending on the previous magnetic state of thel machine and whether thecar is approaching the landing or returning to the landing after an overrun. Such variations in E. M. F. values cause undesirable variations in the operation of the car during the leveling period.

One feature of the invention is to cause more uniform operation ofthe elevator car during the leveling period by obviating the effect-s of hysteresis.

Where power operated car gate and hatchway door mechanism is employed Ain elevator systems', it is desirable to have the mechanism Operate in such manner as to effect the movement of the gate and door into Open positions bythe time that the'ca'r has stopped at the floor. Such operation is advantageous particularly because ofthe amount of time which is saved. In high speed elevator systems, the time gained in making each stop isan important factor and, when the gain for a whole trip is considered, it'may be seen that the operating efficiency of the whole system is raised considerably. It is further in the interest of 'Operatlng etliciency, where mechanism is employed to bring the car to a level with the desired landing in stopping, to cause the automatic gate and vdoor opening operation to occur during the. leveling period. Thus with the gate and door opening mechanism and leveling mechanism operating simultaneously, the car gate and hatchway door are fully opened as the car is brought to a stop level with the landing. In the event that the levelwith a passenger in the act of stepping into or out of the car.

Another featureof the .invention resides in minimizing the possibillty of occurrence of excessive speeds during! the leveling period. f

Other features and advantages will become apparent from the following description, taken in connection with theaccompanying drawings wherein one embodiment of the invention is illustrated and in which:

Figure 1 is a diagram of an elevator control v system Figure 2 is a fragmental schematic view ofl a portion of the elevator system, illustrating particularly the manner in which the generator field winding is controlled during the leveling operation; and

Figure 3 is a hysteresis curve employed to illustrate the invention.

Referring to Figure 1, no attempt is made to show the coils and contacts of the variousv electromagnetic switches in their associated positions,'a straight diagram being employed wherein the coils and contacts of the various switches are separated in Such manner as to render the circuits involved relatively simple. switches and apparatus are separated in the interest of simplifying the diagram. For a clearer understanding of the invention, the stationary contacts of the switches are illustrated in cross section. It is to be understood that the system in which the invention is illustrated is chosen merely for convenience of description` and that, although de scribed in conjunction with a car switch controlled system, the invention is equally ap plicable to;` other types of elevator systems such as pnshbutton control systems and to other systems employing a work motor supplied with current from the generator of a motor generator set.

The motor generator set comprises a driv- Also the Yparts of other Y' and therefore the voltage applied to the eleing motor 11, illustrated for convenience of description as ofthe direct current type, and a variable voltage direct current generator 12. The armature of the driving motor is designated 13 and its field winding 14. The armature of the vgenerator is deslgnated 15 and its series field winding 16, its se arately excitedfield winding being arrange in two 'portions 17 and 18. ,The elevator motor is designated as a whole by the numeral 20, its

armature being desi ated 21 and its field winding 22. An ad]ustable resistance 23 is arranged in shunt to the generator series field winding. Discharge resistanees 24 and 25 are provided for the portions 17 and 18 respectively. ofthe generator separately excited field winding. Discharge resistance 26 is provided for the elevator` motor field winding 22,. A resistance 27 is provided for controlling the strength of the generator field *,vator motor armature during car switch operation. Another resistance 28 is provided for controlling the strength of the generator separately excited field during leveling opertively.` 38 is the armature and 40 is the field v winding of the motor 41 for movin-g the rollers of the leveling switch into position to clear the leveling cams. 42 is the armature and 43 is the field winding of the door control motor 44. 45 and 46 are the direct current supply mains. 47 is a double pole knife switch for connecting the system to the supply mains. In order to suit the type of diagram employed, the blades of this switch are shown separated. The car switch is designated' as a whole by the numeral 48. 50 is the safety switch in the car. The series of door contacts are indicated by a single set of contacts 51. The gate contacts are indicated as 52. The various safety, limit, stop and einer ency switches are omitted in order to simp ify the description.

The electron'iagnetic lswitches have been designated as follows:

A-potential switch,

y B-upl main direction switch,

C-down main direction switch, Dflfirst accelerating switch. E-second accelerating switch, F '-series field switch,

T5"V .l G-Selies field relay,

H-main brake and field switch,

ample, `contacts B 111 are contacts on the Xp main direction switch, while actuating coil 53 is the coil that operates the potential switch. The electromagnetic switches are shown in their deenerglzed positions. Reactanees are similarly designated by the character X. y y

Upon the closing of the knifeswitch 47 the driving motor 11, elevator motor field winding 22 and potential switch actuatin Vcoil A 53 are energized, the circuit for coil 53 being through safety switch 50. The

i driving motor starts in operation, bringing the generator -12up to full speed. The series field winding and starting means for the driving motor are omitted to simplify the description. With the elevator motor at rest, the current supplied to its field winding 22 is reduced by section 54 of resistance 29, providing what may be termed a standing field. The circuit for the elevator motor` field winding may be traced from the left-` hand blade of switch 47, line 55, by way of line 56 through field winding 22, resistance sec-tion 54 and second accelerating switch contacts E 57, line 58, to the'right-hand blade of switch 47. It is not desired to apply full line voltage to the field winding 22 when the elevator motor is not in operation because of increased power consumption. On the other hand, it is not desired to have this field winding deenergized with the elevator motor at rest as a matter of safety and because of the time constant involved in building up. The potential switch, upon operation, causes the engagement of contacts A 60 and A 61, preparing the circuit for the generator separately excited'field winding, the electromagnetic brake release coil and the control circuits. The condition of the circuits so far described might be termed normal.

Referring briefly to Figure 2, the car switch 48 comprises a set of up contacts 62, 63, 64, 65 and 66 and a set of down contacts 67, 68, 69, 70 and 71. A contact segment 72 for bridging the contacts of each set 'is `mounted on the segmental support 73 of insulating material. A cani 74 is formed on` the support above the pivot point 75. The

.ferred to provide centering springs (not shown) on the car switch to cause it to be returned to off position when released by the operator. t

Referring back to Figure 1. assume that the system is designed for an installation of several oors and that the car is at rest at the first fioor with the gate and door open. v1n the starting operation, the operator first gives the car `switch a slight initial movement to effect the closure'ot the gate and door switch 78. For convenience of description, this switch is arranged to complete a circuit t'or the door control mot-or switch actuating coil J 82. This circuit may be traced from the left-hand blade ot' switch 47, by way of line 55 through contacts A 60, by way of line 83 through coil J 82. resistance'84 and switch 78` line 85. switch 50, line 86, line 58, to the right-hand blade of switch 47. The door control motor switch, upon operation, causes the en, ragemrl:.nt of contacts J 87, completing the circuit for the door control motor 44. This `circuit may be traced from the lett-handv 'blade of switch 47. by way'ot` line 55 through contacts A 60, `by way of line 88 through contacts J 87, door `control motor field winding 43 and armature 42, by way of line 58 through 'contacts A 61, to the right-hand blade of switch v47.

Referring again to Figure 2, motor 44 op-- erates pneulnatic gate and door operating mechanism, as for example through linkage 90 to move valve-9171er gate engine 92- to gate closed position and to withdraw the retiring cam 93 yfrom engagement with the roller provided on the end of the door en 'ne valve lever 94. The lever 94 is operate by a spring to move valve 95 for the door engine 96 to door closed position. The gate and door engines operate through mechanism not shown to close the car gate 99 and hatchway door`109. It is to be understoodthat a door,-

is provided in the hatchway at each land-ing. Referring back to Figure 1, if the operator, after he has closed the gate and door, desires toopn them, or if he desires to arrest their to' Y VJ 82 and the separation of contacts J 87. In

movement, he may do so b v releasing the car switch to return to o position. This causes 'the opening of the gate and door switch 78 with. the lconsequent deenergization of coil this manner, the circuit for the motor 44 is broken. The spring 97 shown in Figure 2,

operates upon the deenergi'zation of motor 44 to move valve 91 and, through cam 93'and 1ev more the car switch to full operated position to start the car in the. up direction. It is to be noted that the gate and door switch 7 8 remains in closed position so long as the car switch is moved out of neutral7 position. lvpon the engagement ot Contact segment 72 and contact 64. circuits are simultaneously completed for the op positely wound coils N 98 and N 100 of the sequence relay, actuating coils R 240 of the leveling control relay,

ll 101 of the main brake and field switch and B 102 ot' the up lnain direction switch being in the circuit for coil N 100. I: 1`he engagement of thc contact segment and contacts 65 and 66 prepares circuits for the actuating coils of the accelerating switches.

The circuit for coil N 98 of the sequence relay may be traced from the left-hand blade of switch 47, by way ot' line 55 through contacts A 60, by way of line 103 lthrough coil N 98 and resistance 104, contacts G2 and 64 of the. car switch, by way of line 105 through contacts C 10G of the down main direction switch, line 85, to the right-hand blade of switch 47 as above traced. The circuit for coil N 100 may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, by way of line 107 through door contacts 51, gate contacts 52, sequence relay contacts M 108, and coils R 240, N 100, H 101 and B 102, contacts 63 and 64 ot the car switch, to the right-hand blade ot switch 47 as above traced. The purpose of the sequence relay N is to insure the closure of the gateand doors before starting the car. Coils N 98 and N ,100, being differentially wound, oppose each other, when energized simultaneously,

venting the operation of the up main direc-- tion switch to effect thelstarting of the car.

100, maintaining the se-4 The gate and door switch 78,'therefore, is closed by the initial movement of the car swtchlso that the gate and door contacts mayV be closed before the engagement of segment 72 and contact 64. However, if the car switch is moved into position where segment 72 en- Thus it is impossible to start the car on thev door or gate contacts. 'i

Assuming that the se uence relay has op erated, in order to start t e car the car switch 1s returned to a position with segment 72 disengaged from contact 64, deenergizing coil N 98 to permit contacts N 108 to reengage. If the gate and door are closed, the car switch may be returnedaimmediately to full on position. Otherwise, closing of the gate and door must be effected before the car switch is movedinto full on position. l

The leveling control relay R, upon operation, causes the separation of contacts R 241 in the circuit for the actuating coils'of the leveling direction switches. The purpose of this arrangement will be described later.

It is preferred'to provide the main direction switches with a mechanical interlock to prevent their simultaneous o eration. Such an interlock may be of the orm olf a walking beam pivotally mounted for engagingcatches on the armatures of these switches. Upon operation of the up main direction switch in response to the energization of its f actuating coil B 102, contactsB separate and contacts B 111, B 112 and B 113 engage. The separation of-contacts B 110 breaks the circuit leading from the car switch down feed contact 69, contacts B 110 and the corres onding down direction switch contactsl 106 serving as electrical interlocks as is well understood in the art. The engagement of contacts B 113 prepares the circuit for the up v main direction switch holding coil B 115 and the main brake and field switch holding coil H 116. The engagement of contacts B 111 and B 112 completes a circuit for the generatoi` separately excited field winding. This circuit may be traced from the left-hand blade of switch 47, by way of line '55 through contacts A 60, resistance 27v and contacts B 111, by way of line 117 through field control switch contacts L 118, through portion 18 of the separately excited-field winding, by way of line 120 through contacts L 121' and portion 17 of the separately excited field winding,4 by Way of line 58 through contacts B 112 and contacts A 61, to the right-hand blade of switch 47. i

The main brake and field switch H operates simultaneously with the main direction switch B. Switch H, upon operation, causes the separation of contacts H 119, H 122 and H 123 and the engagement of contacts H 124, H 125, H 126 and H 127. Thel separation of contacts H 119 disconnects the generator sep` arately excited field. winding from the generator armature. The purpose of this arrangement Will be explained later. Contacts l IH 122, are in the circuit for the field control switch actuating coil L 128. The pur ose of this arrangement also will be explaine later. The separation of contacts H 123 disconnects resistance 33 from across the brake release coil 30. Resistance 33 being Iof low ohmic value, its disconnection before contacts H 4124 engage prevents excess power consumpvtion from mains 45 and 46. The engagement of contacts H 127 establishes a circuit for the door control motor maintaining relayfactuating coil H130. This circuit may be traced from the left-'hand blade of switch 47, by way of line 55 through contacts A 60, by way of line 83-through coil J 82, by way of line 131 through up leveling direction switch contacts LB 132, down leveling direction switch contacts LC 133, contacts H 127 and coil K 130, line 85, to the right-hand blade of switch 47 as previously traced. The engagement of contacts H further prepares the circuits for the actuating coils of the accelerating switches. The engagement of contacts'H 126 shortcircuits section 54 of the elevator motor field resistance 29, permitting the motor field to ment of contacts H 124 completes the circuit for the brake release coil 30. This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, by way of line 134 through contacts 135 operated by the brake, brake release coil 30 and contacts H 124, by way of line 58 through contacts A 61, to the right-hand blade of switch 47. v

The door control motor maintaining relay coil K in the circuit above tracedl is subject to the potential drop across resistance 84. The system is arranged so thatthe voltage thus applied to coil K 130 is sufficientto effect the operation of the relay. Contacts K 136 engage, upon the operation of the relay, to by-pass contacts H 127. The purpose of this arrangement will be seen from later description.

The brake release coi] 30 being energized,

As the brake releases, the brake switch contacts separate to insert cooling resistance 137 in series with the brake release coil. These brake switch contacts are preferably ar# ranged to be separated at the end of the releasing operation. Separation of contacts 135 also breaks the short circuitaround coil O 138, permittingthe operation of the accelerating relay O. This relay operates to cause the engagement of contacts O 140, completing lll the circuit for the first accelerating switch actuating coilrD 141. The purpose of this arrangement is to utilize the time constant of the brake for timing the acceleration 'of the motor, more specifically, for timing the operation of the first accelerating switch. Although the brake release coil is energized at the same time that poweriis supplied to the `motor, the brake shoes do not lift at once because of the inherent time constant'of the brake magnet and because the brake shoes andV lever arms represent considerable mass to Y be set in-motion. The circuit for coil D 141 completed by contacts O 140 may be traced from the let-handblade of switch 47, by way of line 55 through contacts A 60, by way of line 107 through the door contacts 51, gate `circuit for the leveling ,switch motor 41'.

This circuit maybe traced from the lefthand `blade of switch 47, by way of line 55 through contacts A 60, by way of line 147 through contacts D 143, field windin 40 and armature 38 of motor 41, by vway o line 58 through contacts A 61, to the right-hand blade of switch- 47. Thel leveling switch motor acts, upon energization, to move the v leveling switch operating .rollers so as to clear the leveling cams during movement of the car. This operation will be explained later. The engagement of contacts D 144 completes the circuit for holding coils B 115 and H 116. This circuit may be traced from the lett-hand blade of switch 47 by way of line through contacts A 60, by way of line 148 through coil H 116 and contacts D 144, by way of lline 150 through coil B 115 and contacts B 113, line 151, line 85, to the right-hand blade of switch 47 as previously traced. The'purpose of the energization of these holding coils will be seen from later description. AThe engagement of contacts D 146 completes the circuit for the second accelerating switch actuating coil E 152. This -circuit maybe traced from the left-hand blade of switch 47 by way of line 55 through contacts A 60, by way of line 107 through door contacts 51, gate contacts 52 and contacts N 108, by way of line 142 through contacts H 125, by way of line 153 through' contacts D 146, reactance X 154 and coil E 152, car switch contacts 66 and 64, to the righthand blade-of switch 47 as previously traced. The engagement of contacts D 145 shortcircuits .section 155 of resistance 27, increasing the voltage applied to portions 17 and 18 of the generator field winding. Thus the ,generator E. M. F. is increased, increasing the speed of the motor. W

. The second accelerating switch E does not operate immediately the circuit for its actu` ating coil is completed, its action being delayed by the effect of reactance X 1-54.4 Upon operation, contacts E 156 and E 57 separate and contacts E 157 and E 158 engage. The separation of contacts E 156 removes the shunt circuit around a portion of resistance 160. The separation of contacts E 156 before contacts E 158 engage prevents excess power consumption from mains 45 and 46. The engagement of contacts E 158- completes the circuit for the irst acelerating switch holding coil D 161 and the maintaining relay actuating coil M 162. This circuit `may be traced from the left-hand blade of switch 47 .by way-of line 55 through contacts A 60, by way of line 151 through contacts E 158, re-

actance X 163, coil D 161 and coil M 162, line 85, to the right-hand blade of switch 47 as previously traced. The maintaining relay contacts M 164 are thus caused to by-pass contacts D 144. The purpose of this arrangement will be described later. The en-` gagement of contacts E 157 short-,circuits sections 165 and 166 of resistance 27 to` invcrease the voltage applied to portions 17 and '18 of the generator separately excited field winding. The E. M. F. of the generator,y therefore, increasesto its full value and the speed of the elevator motor increases. The separation of contacts E 57 removes the short-circuit for section 167 of resistance .29 in the elevator motor eld winding circuit, bringing the elevator motor up to full speed.

The starting of the car in the down direction is. accomplished in a similar manner and will be only brieiy described. The operator 'first moves the car switch into position to cause the closure of the gate and door and then into full on position where its contact segment 72 bridges contacts 67 68 69, 70 and -71. Thus the circuit is completed for the downv main direction switch actuating coil C 168. This circuit may be traced from the left-hand blade of switch 47 through coil H 101 as previously traced, by way of line 170 through coil C 168, car switch contacts 68 and 69, by way of line 171 through contacts B 110, line 85, to the right-hand blade of switch 47 `as previously traced. The circuit for coil N98 is by way of line 172. The circuit for coil D141 is by way of line 173. The circuit for coil E 152 is-by way of line the down main ,direction switch is designated C178. FurtherA than 174. The down main direction switch, upon this, the operation of starting the car in the down direction is the same as described for starting it in the up direction.

Assume that the car is running in the up direction and that the operator centers the car switch between the second and third iloors in order to stop at the third floor landing. Thus the-contact segment 72 moves off contacts 66, 65', 64 and 63 and the circuits for the second accelerating switch actuating -coil E 152, first accelerating switch actuating coil D 141,` main brake and field switch actuating coil- H 101, up main direction switch actuating coil B 102, leveling control relay coil R 240 and sequence relay coils N 98A and N 100 are broken. The leveling control relay Y and the second accelerating switch drop out y and X136 in parallel an this relay will. be explained, later.

The second accelerating switch, u on dropping out, causes the separation o contacts E 157 and E 158 and the reengagement of contacts E57 and E156. The separation of contacts E 157 reinserts sections 165 and 166 of resistance 27 in series with the generator separately excited field winding to decrease the E. M. F. of the generator. The engagei ment of contacts E57 short-circuits section "D and maintaining rela M do not coils.

167 of resistance 29, increasing the strength of the elevator motor field for the sto ping operation. With the nerator E. F. lowered and the strengt of the elevator motor field increased, lthe speed of the elevator motor is decreased. Theseparation 'of contacts E 158 breaks the circuit for holding coil D 161v and coil M162. The first accelerating switch rop out immediately, however, t eir action being delayed by the eect `of reactance X 163 in series `with the coils" and vthe discharge resistance 169 in arallel with the reactance 'and the short-circuit a portion of resistance 160 is effective to prolong the time element of the switch and relay. The time element maybe adjusted to the'desired value by changing the amount of the resistance portion shortcircuited. Relay M is preferably adjusted to @holdin at a smaller current value than the accelerating switch D. This may be readily accomplished due to the fact that the re ay is much smaller and therefore lighter in e deenergization -of .coils e engagement of contacts E 156 to.

incassa' y struction than the accelerating switch and requires less current to hold in.

The rst accelerating switch, upon dropping out, causes the separation of contacts D 143, D 144, D 145 and D 146. The separation of contacts D 144 is in prepartion for the next starting operation, contacts M 164 remaining in engagement to maintain holding coils H 116 and B 115 energized. The separation of contacts D 146 also is in preparation for the next starting operation, the circuit for coil E 152 having been broken by the movement of the car switch as above described. vThe vseparation of contacts D 145 removes the short-circuit for section 155 of resistance 27, decreasing the strength of the generator field. Thus the generator E. M. F. is again decreased andthe speed of the elevator motor is reduced.` It is to be understood that resistance 27 may be controlled in any number of steps, tw o being shown merely for convenience of description.

The separation of contacts AD 143 deenergizes the leveling switch` mot/o1' 41. In this manner the operating rollers 'of the leveling switch are extended for Iengagement by the leveling cams. Referring, briefly to Figure 2, the leveling switch motor is operatively connected to the leveling switch by means of an arm 180 on the motor shaft, a connecting link 181 and a lever` 182. In the starting operation, the motor 41 being energized, arm

180 rotates, acting through link 181 and lever` l 182 to move the leveling switch as a whole about a pivot. In tliis manner the leveling switch operating rollers 183 and 184 are moved into position where they do not engage the leveling cams 185 and 186 during motion of the car, a stopl being provided to determine the extent of t e movement. It is to be understood that leveling cams are provided for each floor. The leveling switch is ivoted on a bracket 187 secured to the car rame. In the stopping operation, upon the deenergization of the leve 'ng switch motor, as ring not shown) moves the lever 182 an there the first described position with the rollers 183 and 184 extended for engagement by the leveling cams. Each pair o leveling switch contacts 34, 35, 36 and 37 comprises'a stationary contact and a movable contacto er.- ated by the engagement of its correspon roller and leveling cam. The fast spee contacts 36 and 37 are arran ed to se arate before their corresponding `s ow spec contacts 34 and` 35 in the leveling operation.v

ore the leveling switch back into l Springs (not shown) are provided for cau'sy ing the separation of the contacts of the pairs as the leveling operation is e'ected and stops are provided for determinin the extent of movement of the rollers as t leveling cams. g v

It will be assumed that the car has not reached the and .the up leveling ey ride oithe v completes a circuit for the u leveling direction switch actuating coil B 188 and the leveling brake and eld switch actuating coil LH 190. This circuit may betraced 'from the left-hand blade of Switch 47, by -way of line 55 through contacts A 60, line 191, leveling switch contacts 34, by way of line 192 through coil LB 188 and c oil LH 190, by

pleted.

- will be referred to later.

way of line 85 through leveling control relay Vcontacts 241, to the right-hand y blade of switch 47as previously traced. The engagement of the leveling switch up fast speed cons tacts 36 completes the circuit for fast speed leveling .relay actuating coil LF 193. This circuit may be traced from the left-hand blade of switch'47, by way of line 55 through contacts A60, line 191, leveling switch contacts 34, line 194, leveling switch contacts 36, by way of line 85 Vthrough coil LF 193 and contacts B 241, tothe right-hand blade of switch 47 as previously traced. It is to be noted that, diie to the'fact that the circuit for Icoil LF 193 is throughleveling switch slow speed contacts 34, the circuit for coils LBV 188 and LH 190 must be made in order that the circuit for coil LF 193 may be com- The up operation', causes the separation of contacts LB 132 and the engagement of contacts LB 195, LB 196 and LB 197. Contacts LB 132 Contacts LB 195 and LB 196 by-pass main direction switch contacts B 111 and B 112 respectively invthe circuit for the generator separately excited field winding. The engagement of contacts LB 197 completes the circuit for-up series ield relay' actuating coil G 198 and up hard brake switch actuating coil P 200. This circuit may be traced from the left-hand blade of switch 47, by way of line through contacts A 60, by way of line 201 through contacts LB 197, coil G 198, coil P 200, and portion 202 of reactance X 203, line 204, by way 'fof line 58 through contacts A 61, to the righthand blade of switch 47.

The leveling brake and field switch, op-

erating simultaneously with the up levelingl 'direction switch, causes the separation 'of Y contacts LH`205, LH 206 and LH 212 and the engagement of contacts LH 207, LH 208, LH 210 and LH 211. Contacts LH 205 are in the circuit for resistance 33 across the brake release coil. Contacts LH 206 are in series with contacts H 119 in the circuit for connecting the generator separately excited field ywinding to vthe generator armature. Contacts LH 212 break the shunt circuit, comprising resistance 160, for coils D 161 and M 162. Contacts LH 207 by-pass contacts H 124 in the` circuit for the brake redrop out.

. contacts LH 210 is without effect at this time as-contacts H 122 are'separated. The purpose of contacts LH 205, LH 206, LH 207, LH 208 and LH 210 will be seen as the -description proceeds. Contacts LH 211, upon their-engagement, prepare a circuit for short-k circuiting section 155 andA adjustable section 165 ofresistance 27 for the generator separately excited iield winding.

The .fast speed leveling relay, upon operation. causes the engagement ot contacts LF 213 and LF 214. The engagement of contacts LF 213 prepares a circuit for shortcircuting the adjustable section 166 of re;

sistance 27 for the generator separatel excited iield winding. The engagement o contacts LF 214 by-passcs contacts LB 132, LC

133, H 127 and K 136, coil K 130 and switch `7 8 through resistance 84 in a circuit for coil J 82 of the door control motor switch. Since the engagement oi contacts LF 214 gencr-` vally occurs substantially simultaneously with v the separation of contacts LB 132, the switch J does not drop out. Even ifswitch J should drop out, the immediate reenergization of J coil J 82 upon the engagement of contacts leveling direction switch LB. upon LF'214 would prevent the operation of the gate and doorA operating mechanism due to the time required for the mechanism to start in operation. The circuit for the door control inotor maintaining relay coil K 130, however, is broken by the separation of contacts LB 132. v

The separation of contacts LH 212 to break the circuit forkresistance 160 as above set forth causes relay M to drop out and separate contacts M 164. As a result the circuit for holding coils B 115 and H116 is broken, permitting the up main direction switch and main brake and iield switch to causes the separation of contacts B 111, B 112 and B 113 and the engagement of contacts B 110. The separation of contacts B 113 and the engagement of contacts B 110 is in preparation for the next starting operation. The separation of contacts B 111 and B 112 is without effect as they are ley-passed by contacts LB 195 and LB 196 to maintain the energization for the generator separately ex cited eld winding. The switch H, upon dropping out, causes the separation of contacts H 124, H 125, H 126 and H 127 and the engagement of contacts H 119, H 122 and H 123. The separation of contacts H 125 and H 127 is .in preparation for the next starting operation. The separation of contacts H 124 and H 126 is without e-Hect, the circuit for the brake release coil 30 being maintained by contacts LH 207 and section Switch B, upon dropping out,

. as the circuit for reconnectin 54 of resistance 29 remaining short-circuited by contacts LH 208. The engagement of contacts H 119 and H 123 also is without effect y the generator separately excited field winding to the generator armature is maintained broken by contacts LH 206 and the shunt circuit for the -brake release `coil 30 comprising resistance 33 is maintained broken by contacts LH 205.

vThe engagement of contacts H 122, however,

completes the circuit for the field control switch actuating coil L 128. This circuit may betraced from thel left-hand blade of switch 47, by way of line 55 through contacts A 60, by Way of line 215 through contacts H 122, contacts LH 210 and coil L 128, line 85, to the y right-hand blade of switch 47 as previously traced.

The field control switch L, upon operation, causes the separation of contacts-L 118 and L 121 and the engagement of contacts L 216, L 217, L 218 and L 220. Thel separation of contacts L 118 and L 121 breaks the circuit for portions 17 and 18 of the generator separately excited field winding. The immediate engagement of contacts L 216 and L 217, however, reconnects the portions to the mains. The polarity of the latter connection is such that the current supplied to portion 18 fiows in such direction asto create a magnetizing force which opposed lthe magnetizing force due to portion 17.

charge resistances 24 and 25 act to not only the changes in generator E. Fffdue to the reinsertion of resistance 27 in circuit with the separately excited field windingin steps, but also the change due to the disconnection and reconnection of the portions 17 and 18 to the mains.

The engagementof contacts L 218 connects resistance 28 in parallel with field winding portion 18 so that the current in portion 18 is less than that in.. portion 17 Thus the magnetizing force due to portion 18 is less than that due to portion 17 The engagement of contacts L 220 completes the short-circuit for' resistance 27 through the fast speed leveling relay contacts LF 213. With contacts L 118 and L 121 separated and contacts L 216, L 217, L 218, L 220.a nd LF 213 in engagement, an E. M. F.1is generated which causes the-elevator motor to run at a suitable fast leveling speed, aswill be seen from later description.

Relay G and switch Pdo not operate immediatelytheir actuating coils are energized,

ltheir action being delayed by reactance X 203.

Switch P, however, is adjusted to operate almost immediately' and, upon operation, causes the Jseparation of contacts P 221, disconnecting resistance 32 from across the brake release coil 30. Relay G, upon operation, causes the engagement of contacts G 222, completing the circuit for the series field switch actuating coil F 223. This circuit may be tracedfrom' the left-hand blade of switch-47, by way of speed contacts 36, deenergizing fast s line through contacts A 60, by way of line 224 throu h contacts G 222 and coil F 223, by way o line 58 through contacts A 61, to

the right-hand blade of switch 47. Switch,

F, upon operation, causes the separation. of contacts F 225, breaking the circuit including resistance 23 in shunt to Athe generator series field winding 16. The generator series field is so wound that, without the parallel resistance 23, it would have too great an effect for proper operation of the car. The desired compounding is -obtained by employing the U on separation of low resistance shunt. contacts F 225, the strengt of the series field is increased for the leveling operation so as to aid in bringing the motor to a stop. The short delay in the action of--relay G, and therefore switch F, upon the initiation of the leveling operation, is desirable in order that the current in the generator armature-elevator motor armature circuit may ad'ust itself to such 'a value'that proper series eld strength duri-n taine vAs the car nears the'third floor landing,

vits slow leveling speed. The separation of contacts LF 214 breaks the circuit for the door control motor switch coil J 82. Switch J upon dropping out, causes the separation of contacts effecting the automatic gate and door open ing operation. The gate and door operating mechanism functions in the same manner as described for opening the gate and door in response to centering the car switch. In this manner the automatic gate and door .opemng t operation is timed so at the gate and door open as the car stops at the landing. It is to be noted, however, that the automatic gate and door opening operation cannot take place the leveling operation `may Yob.

87 to deenergize the motor 44, thus until the leveling switch fast speed contacts separate.

Short] before the r reaches the exact level wit the landing, 'the roller 183 rides of the obli ue surface of cam 185, thereby |ep-'A p arating t e leveling switch up slow speed contacts 34. The circuit for coilsLB 188 LH 190 is thus broken. Switch LH drg out, causing the separation of contacts 207, LH' 208, LH 210 and LH'211rand the` reenggement'of contacts LH 205, LH 206 and H 212.A The enga ment of contacts v 212 is in preparation or the next starting lasi operation. The separation of contacts LH 211 also is in preparation forthe next starting operation, the circuit for the generator separately excited field winding being broken asa result ofthe separation of up leveling direction switch contacts LB 195 and LB 196 as will be set forth below. The separa tion of contacts LH 207 breaks the circuit for the brake release coil and the accelerating relay coil O 138. Due to the fact that the coil 30 discharges into resistance 31 of relatively high ohmic value, a hard7 application of the brake is obtained. The accelerating relay 0 drops out, separating contacts O 140 in prep-` aration for the next starting operation. The separation of contacts LH -208 reinserts section 54 of resistance 29 in series with the elevator motor field winding, reducing the current therein to a standing field value.

The separation of contacts LH 210 breaks the circuit for the field control switch coil L 128, the switch dropping out in preparation for the next starting operation. 1 It is to be noted that the separation of contacts L 216 and L 217 and the engagement of contacts L 118 and L 121 reconnects the portions 17 and 18 of the separately excited field winding for cumulative action. The reengagement of contacts LH 206 reconnects the generator sep# arately excited ield winding to the genera-4 tor armature. The polarity of this connection is such that the generator sends current through the field winding in such manner as to oppose the flux which produces the generator E. M. F., thus tending to destroy the residual flux of the generator field.

Up leveling direction switch LB, dropping out along with switch LH, causes the separation of contacts LB 195, LB 196 and LB 197 and the engagement of contacts LB 132. The engagement of contacts LB 132is in prepara tion for the next starting operation. The separation of contacts LB 195 and LB 196 disconnects the generator separately excited field winding from the mains as indicated above. The separation of contacts LB 197 breaks `the circuit for coils G 198 and P 200. The

relay G drops out immediately, but the dropping out ofswitch P is delayed slightly due to the efl'ect of the reactance X 203 and discharge resistance 226. It is to be noted that the discharge current for up c oil P 200 and the feactance passes through down coil P 227 in such direction as to cause coil P 227 to assist coil P 200 in maintaining switch P in operated condition. Relay G, upon dropping out, causes thev separation of contacts G 222 to deenergize coil F 223,-switch Ilivdropping out in turn to cause thev engagementoicoro` tacts F 225.- The'engagementof contacts F reconnects resistance 23 in parallel with thegenerator seriesfield winding 16. Switch P, upon dropping out, causes the engagement of contacts P 221.

Thus the brake being applied and the generator separately excited field winding being disconnected from the mains, the car is brought to rest level with the third floor landing. The engagement of contacts LH 205, along with the delayed engagement of contacts P 221, places discharge resistances 32 and 33 in parallel with the brake release coil 30 to soften the application of the brake.

With the sequence of operations as above described the car will be slowed down and stopped level with the desired landing with` LF to bring the car to a level with the floor.

In the event that the car switch is centered late in the stopping operation, as for example when the leveling switch operating roller` strikes the leveling cam upon the dropping out of the first accelerating switch D, the immediate separation of contacts LH 212 forces the dropping out of the main direction switch and the main brake and field switch to permit the immediate change of the field winding connections and thus slow down the elevator motor more rapidly. In this manner the tendency for the car to overrun the door is reduced.

Should an overrun occur, however, the system is arranged so that the operation of the switches is modified. Assuming in the above example that the car overruns the third fioor landingI to the extent of causing the engagement of leveling switch down slow speed contacts 35, a circuit is completed for down leveling direction switch actuating coil LC 228 and coil LH 190. This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, line 191, contacts 35, by way of line 230 through coil LC 228, by way of line 192 through coil LH 190, line 85, to the right-hand blade of switch 47 as previously traced. Contacts LH 205, LH 206 and LH 212 are separated and contacts LH 207, LH 208, LH 21() and LH 211 are engaged so that the circ-uit for resistance 33 across the brake release coil is broken, the brake release coil isv energized, resistance section 54 for the elevator motor field winding is short-circuited and the field control switch actuatin coil L"128'isv energiz'ed. .Contacts L 212 "insure the dropping out of the 'main directionfswitch. Switch'L operates as previously-,described to cause the separation of contac ts L 118 and L 121 and the engagement of contacts izo' . contacts LC 133 and the engagement of contacts LC 231, LC 232 and L 233. The separation of contacts LC 133 is without particular efiect at this time. The separation of contacts LH 206,L 118 and L 121 and the engagement of contacts LC 231, LC 232, L 2,16 an L 217 causes the disconnection of the separately excited field winding from the generator armature and the connection of portions 17 and 18 of the winding to the mains in such manner as to cause thelr magnetizing forces to act in opposition. The engagement of contacts LH 211 and L 220 short-circuits resist-v ance sections 155 and 165, causinfr the application of the desired voltage to the generator separately excited field winding. Resistance 28, reconnected across portion 18 of the winding, as before causes less current flow through portion 18 than through portion 17. Due t0 the reversal of the flow of current through both portions of the separately excited field winding from that during the leveling operation upon the car approaching the floor in the up direction, the car is caused to start in the down direction.

The engagement lof contacts LC 233 completed a clrcuit for the down series field relay actuating coil 234 and the down hard brake switch actuating coil P 227. This circuit may be traced from t-he left-hand blade of switch 47, by wa of line through contacts A 60, by way o line 235 throu h contacts LC 233, coil G 234 coil P 227 an portion 236 of re- 'actance X 203, line 204, by way of line 58 through contacts A 61, to the right-hand blade of switch 47. Relay G and switch P do not operate immediately upon the engagement of contacts LC 233. When approaching the floor in the up direction, the current flowing through reactance portion 202 caused a flux to be built rip in the reactance X 203 in one direction. pon the separation of contacts LB 197, the current in the reactance and coil P 200 discharged into resistance 226 tendingto maintain the flux built up and, as previously explained, switch P in operated condition.' Upon the enga ement of contacts LC 233 on the overrun, t e current supplied to coils G 234 and P 227 must reverse the flux in the reactance, thus taking a longer time to build up to a value sufficient to cause the operation of relay G and switch P. Thus Vcontacts F 225,I depending f or their operation upon the operation of relay G,.remain closed teinporarily to 'insure that the current in the generator armature-motor armature circuit has fallen to a low value. Slnce the current in the series field winding may be flowing inv a direction such as to cause the generation of an M. F. which ,is of proper polarity for operating the car in thev down direction, immediate increase in the strength of tno sefries field might result in an overnm in the down direction. As the car returns to the floor, it is stopped by the separation of the leveling switch slow speed contacts 35 in a manner similar to that described. for approaching the floor'in t-he up direction.

If the overrun is great enough to cause the enga ement of the leveling switch downfast spee contacts 37 as well as the levelin `switch down slow speed contacts 35, coil L 193 is energized. As before, relay LF causes the engagement of contacts LF 213 to short-circuit resistance section 166, increasing the generator voltage and causing the elevator motor to run at its fast leveling speed. Relay LF also causes the en a elnent of contacts LF 214 to energize coiPJg82' again in the event that it has become deenergized. Upon such an overrun, the automatic gate and door openin operation does not occur until contacts L 214 separate, as previously described. Further than-this, the operation on an overrun is as above described.

It is to be understood that the operator may control both the acceleration and retardation of the car by moving the car switch in steps. In the event that the operator starts the car from a floor by moving the car switch only so far as to engage one of the feed contacts, for example contact 64, the up main direction switch B and main brake and field switch are operated to complete the circuit for the generator field winding, by the enagement of contacts B 111 and cont-actsand H, causes the separa-tion of contacts R 241 and thus prevents the energization of the down leveling switch actuating coil LC 228 as a result of the operation of the leveling switch during the upward movement of the car away from the floor.l Contacts LC 231 and LC 232, therefore, do not engage, preventing the establishing of a shunt circuit around the enerator separately excited field winding. 5 move the car switch from one position into the other, for example from up into down position, inury to the system v1s prevented b contacts whichv remains separated until the u direction switch drops out. It is to be lnote that, when the car is suddenly reversed or stopped between'floors or stopped b opening the safety switch 50, the switch ,is not operated. Thus contacts P 221 are in engagement and a soft application. of the brake is obtained.

In variable voltalge control systems of the type wherein the e l'lO hould the operator suddenly with current from the generator. of a motorgenerator set, the generator is required to opcrate over a wide range of E. M. F. values, varying from a maximum in one direction to a maximum in the other. When operating at low values, the E. M. F. generated, with a given field current, may vary over a wide range due to the varying effects of residualflux. This effect is very marked under leveling operating conditions Where low values of generated E. M. F. are employed. Such low values of E. M. F. are usually obtained by permitting only a small amount of current to flow throughthe generatorseparately excited field Winding so as to produce low values of' flux.l Thus the residual flux present forms a large percentage of the total flux and therefore aects the operation ofthe system very markedly. In order that the eects of the residual flux maybe clearly seen, reference may be had to the assumed hysteresis curve shown in Figure 3. This figure illustrates the conditionswhen a small current is supplied to the separately excited field winding of a generator, as during the leveling operation. The magnetizing forces due to this small current are represented as Nl and --NI, depending on whether the car is appreaching the floor or returning to the floor after anoverrun. Assume that the generator armature E. M. F. has been of the value V1 and that later, in attempting to make a landing, the self-leveling operation takes place with the car approaching the floor. The E. M. F. of the generator during this period will be of a value V2. On the other hand, if the car overruns the floor, the E. M. F. of the generatorwill be of a value V3, which value is much less than the value V2. Hence the speed of the elevator motor is much less. The values V2 and V2 of the generator E. M. F. may vary during operation of the system depending upon the previous magnetic state of the machine. Assuming that the E. M. F. values V2 and V3 are those obtained duringV leveling Jfor normal operation, then the values of generator E. M.

F. during leveling will lie somewhere hetween V2 and V2 for other conditions of operation. Obviously, such large voltage variations would result in undesirable variations in .operation under leveling conditions. These variations cannot ybe satisfactorily corrected merely by adjusting the amount of resistance in series with the separately excited field winding. v For example, if the amount of resistance Were decreased in order to raise the value ofv V2, the value V2 also would be increased, resulting in an increasing a5 the fioor after an overrun. lf the effects of tendency to run past the floor. Similarly, if'

justed so as to obtain more uniform operation. This may be accomplished by reversing the polarity of certain of the field poles` The preferred arrangement for effecting this change has already been describedfin connection with Figure'l. The particular arrangement of the separately excited field winding is illustrated in Figure 2.

Referring to Figure 2, it is preferred to group the coils for the north and south poles N and S together to form the portion 17 and those for the north and south poles N1 and S1 together to form the portion 18. The coilsforming the portion 17 are connected in series relation as are those forming the portion 18. l/Vith the switch L in deenergized position, as during car switch operation, the current flows through the coils in such manner as to provide the poles of alternate polarity as indicated. Upon the operation of switch'L during the leveling operation, contacts L 118 and L 121 separate and contacts L 216 and L 217 engage. Although this operation does not affect the direction of the flow of current throughk the coils for poles N and S, it does reverse the current through the coils for poles N1 and S1.` Thus N1 becomes a south pole and S1 becomes anorth pole. If these poles were excited equally, the value of the total E. M. F. at the generator brushes 19 would be substantially zero, since the voltage generated in part of the generator armature is balanced out by a voltage of equal value but opposite polarity generated in the remainder of the armature. By employing a large magnetizing force for each pole, with the magnetizing force for the poles N1 and S1 excited by field winding portion 1.8 of less value than that for poles N and S excited by portion 17, an E. M. F. of low value suitable for the leveling operation may be obtained. In this manner, the iron of the variousl parts of the magnetic circuit. is Worked on high portions of the hysteresis loop where the effect of residual flux is practically nil, and E. M. F.s may be obtained, during leveling operations, the values of which are not aected by residual flux and are practically the same Whether the car overruns or underruns the floor.. This may be accomplished by short-circuit resistance 27 with contacts L 220, LH 211'andl LF 213 and by connecting resistance 28 in parallel with portion 18, employing contacts L 218. The above described arrangement will operate to obviate the effects of hysteresis with generators of other pole numbers, va four pole generator being vchosen merely for convenience of description. In describing the invention, the usual series armature Winding has been assumed. If for any reason, such as due to the manner of winding the generator armature, an E. M. F. is generated upon reversal of portion 18 of the field winding without reducing the current therethrough, it would be of advantage since a resistance of higher ohmic value could be employed for resistance 28. If the E. M. F. were great enough, resistance 28 could be dispensed with entirely. It is to be understood that other arrangements may be employed for causing the mavnetizing force for the poles excited by field winding portion 18 to be different from the magnetizing force for the poles excited by winding portion 17, for example, as by winding the coils constituting winding portion 18 soas to have a different number of turns from the number of turns of the coils constituting windin vportion 17. If such arrangement were emp oyed, resistance 28 might be omitted. 4

This arrangement for the control vof the separately excited field winding also is effective in avoiding the occurrence of excessive speeds of the elevator car during the leveling period. The automatic opening of the gate and door during this period renders this feature of particular importance. In systems employing resistance in series with the elevator motor armature to control the speed of the motor during leveling, or where the voltage applied to the armature of the elevator motor during leveling is controlled by means of resistance in series with the separately excited field winding of the generator which supplies power to the motor, there is always a possibility of all or a portion of the resistance becoming grounded or short-circuited, causing the speed of the elevator motor to increase.' If mechanism were employed, as in the present system, to effect the automatic opening of the gate and door during the leveling period, the sudden increase in sneed might occur while the gate and door were being opened, or after the gate and door were open. when the leveling arrangement is slow in bringing the car to a level with the landing. In the present system, resistance 27 is short-circuited during leveling in order to obtain the desired fast leveling speed. VThus it is impossible to obtain excessive speeds of thel elevator car during the gate and door opening operation by the application of line voltage to the generator separately excited field as the most that could happen would be to cause the carto runat its -fast leveling speed. It is fto be understood that contacts could be provided on the field control switch L to break the circuit for the gate motor maintaining relay coil K 130 lnstead of employing contacts LB 132 and .LC 133 in order to insure that the gate and door would not open unless the field winding connections were changed. v y

As many changes could be made in the f above arrangement and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all .mat-

ter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current to said motor, means for driving said generator, a field winding for said generator, said field windin having a plurality of p0rtions, a source off7 current for. said winding, means for connecting said winding to sald source to cause current to flow in a certain direction through all of said portions to obtain full `speed operation of the car, and means for causing said motor to bring the car to a level with a desired landing in stopping, regardless of whether the car overruns or underruns said landing, said last included means comprising means for causing the flow of current through one of said ortions of` said winding to be in a reversed irection to that through another of said portions.

2. In combination, an elevator car, a motor therefor, a generator for supplying current to said motor, said generator having a field winding, means for driving said generator, a source of current, means for connecting said winding to said source so as to cause the motor to operate the car at a certain speed, and means for causing the motor to bring the car to a level with a desired landing at a slower speed, regardless of whether the car overruns or underruns said landing, said last included means comprising means for reversing the connections for a portion of said winding.

3. In combination, an elevator car, a motor therefor, a generator for supplying current to said motor, said generator havin a field-winding comprising a plurality of coils,

one on each pole piece, a source of current, v

means for connectlng all of said coils to said source in such manner as to ycause the motor to operate'the car at a certain s eed, and means for causing the motor to ring the car to a level with a desired landin at a slower speed, regardless of whether t e car overruns or underruns said landing, said last included means comprising means for reverlssing the connections for certain of said co1 4. In combination, anlelevator car, a motor i therefor, a generatorffor supplying current to said motor, said generator having a field winding comprising a plurality of coils, one on each pole piece, a source of current, means for connecting all of said soils to said source in such manner as to cause the motor to operate the car at a certain speed, and means for causing the motor to bring the car to a level withl a desired landing at a slower speed, re-

gardless of whether the car overruns or underruns said landing, said last included means messes comprising means for reversing the connecl' tions for certain of said coils and means for reducing the amount of current supplied in' the reversed direction to said certain coils below that supplied to the other coils.,

5. In combination, an elevator car, a hoisting motor therefor, a generator for supplying current to the motor, said generator having 4a field winding, a source of current, means for causing the motor to run at a certain speed, said meanscomprising means for connecting said winding'to the source, means for causing the motor to run at a slower speed, said second named means comprising means for reversing the ow ofcurrent through a portion of the winding, a hatchway door, mechanism for causing the opening of said door, and means responsive to the operation of the second named means for causing the operation of said mechanism.

6. In an elevator control system, a motor for raising and lowering the elevator car, a

. generator for supplying current to the motor,

said generator having a field winding, a source of current, means for connecting said field winding to said source so as to cause the motor to run at a certain speed. means for lreconnecting said winding to said source in such manner as to reverse the flow of current through a portionof said winding to cause the motor to run at a slower speed, a hatchway door, mechanism for opening said door, and means for initiating the operation of said mechanism during theoperation of the second g named means.

7. In anelevator control system, a motor for raising and lowering the elevator car, a generator for supplying current to the motor, said generator having a field winding, a source of current, means for connecting said field winding to said source so as to cause the motor to' run at a certain speed, means for reversing the connections for a portion of said 4 winding to cause the motor to run at a slower speed, a car gate, a hatchway door, mechanism for causing the opening of said gate and door,.and means for initiatlng the operation of sald mechanism during the operation of said second named means.

8. In an elevator control system, a motor for raising andar-lowering the elevator car, a generator for supplying current to the motor, said generator having a field winding, a source of current, means for connecting said field winding to said source so as to cause .the motor to run at a certain speed, means for causing the motor to run at a slower speed, said second lnamed means comprising means for disconnecting a portion of said winding and reconnecting it in such manner as to reverse the flow of current therethrough and means for causing lessl current to flow through said portion than through the remainder of the winding, a car gate, a hatchway door, mechanism for causing the opening of said gate and door, and means for initiating the i i operation of said mechanism during the operation of said second named means. l

9. In combination; an elevator car; a hoisting motor therefor, a generator for sup lying current'to said motor, said generator aving a field winding; a source of current;'a resist ance; means for starting said motor, said means comprising means for connecting said field winding to said source in circuit with said resistance and for thereafter short-cir cuiting said resistance to bring the motor up to full speed; means for bringing the car to level with a desired landing in stopping, said. second named means comprising means ,for disconnecting said field winding and re= connecting it to said source with the connections for a portion of the winding reversed so as to cause the motor to run at a fast leveling speed, a second resistance, and means for causing the insertion of said second resistance in circuit with said winding to cause the motor to run at a slow leveling speed; a car gate; a hatchway door; and means responsive to the operation of said means for causing the insertion of said second resistance .in circuit with said winding for causing the opening of said gate and door. i

In testimony whereof, I have signed my name to this specification.

ANTHONY PINTO.

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