the invention relates to a new type of self - powered elevator . specifically , it concerns a self - powered elevator having an inverter controlled asynchronous linear electric motor as counterweight . it is known that in convention electric elevators , the car is attached at the extremity of a rope , the other extremity thereof being equipped with a counterweight . the electric motor draws the car by means of a traction sheave over which a rope passes , itself driven by friction . in practice , to operate in satisfactory conditions , both from the technical standpoint and to ensure the safety of passengers , the car and counterweight have to satisfy the following equation ( 1 ), well known to technicians : ## equ1 ## in which t 1 / t 2 is the ratio between the static forces exerted respectively by the car and the counterweight on portions of the rope located on either side of the traction sheave , c 1 is a constant dependent on acceleration , deceleration and other factors specific to the considered facility , c 2 is a coefficient that takes into account the variation in the profile of the sheave groove due to wear , f is the friction coefficient of the rope on the sheave , and α is the angle of wrap of the rope on the sheave . thus , equation ( 1 ) sets a limit to the reduction in the considered weight ( weight of car ) with respect to the duty load , and determines a relation between the car area and the load , generally in conformity with elevator safety standards . moreover , a rope and sheave system cooperating by friction calls for frequent inspection of the facility . at the present time , energy considerations lead to reducing as far as possible the masses of the moving systems . on the other hand , to provide passengers with adequate comfort , the tendency is rather to increase the volume of elevator cars . to address these contradictory criteria , a number of solutions have been considered in the trade . thus , for instance , it has been suggested to increase the traction exerted on the sheave , while reducing rope wear , by lining the inside of the sheave groove with plastic materials . such improvement , however , only has a limited scope and , furthermore , has few practical applications . another approach has been to have hydraulically controlled elevators , which reduces the masses in motion , but involves an energy consumption far greater than is the case with electrically controlled elevators used to perform similar functions . it has also been suggested to have counterweights to partially compensate the weight of the car , but the cylinder controlling the motion must be able to return without load in the car , thereby limiting the weight compensation by a counterweight . this means that hydraulic elevators are not competitive from the energy savings standpoint . furthermore , the technique is limited by the car &# 39 ; s travel height and speed . yet , another approach is to have a drum system in which car and counterweight have separate ropes which are oppositely wound on the same drum . the solution , however , is no more satisfactory than the previous ones , since for a given travel height of the car , a drum of very great width is required , which is incompatible with the present dimensions of premises set aside for machine rooms . the invention aims to remedy these drawbacks by suggesting a new type of elevator in which the weights may be reduced as compared with existing systems , while providing enhanced comfort to passengers . to this effect , the invention covers a self - propelled elevator in which a car is attached to one extremity of a rope which runs over a sheave , and at the other extremity of which is suspended a counterweight designed to balance the weight of the car and part of the payload , wherein such elevator sheave is a simple return sheave , and the motor system comprises a linear induction motor forming an integral part of the counterweight and cooperating with the counterweight guide rail . provided the facility is equipped with an adequate static braking system , which , however , may be of known type as specified hereinafter , it is possible to overcome the limits generally imposed by the ratio between the area of the car and the payload , thus ensuring increased comfort to users . the motor may preferably be fed with current from a main feeder , connected to a floating battery across a charger , the battery itself being connected to the motor across an inverter . all the components , of known type , may form a constituent part of the counterweight , and have two functions : the first , as usual , being to control the motion of the car ; the second , specific to the elevator according to the invention , wherein the components form a constituent part of the counterweight , being that their mass partially or totally contributes to offsetting the weight of the car and part of its duty load . if desired , the inverter may be of reversible type , thereby further contributing to cutting down current consumption . the battery may be recharged by means of a suspended cable , or preferably by means of socket connectors located at the main landing level . or again , automatic return of the car may be provided when the elevator is idle . alternately , it is possible to eliminate the charger by feeding the battery directly from a solar cell located on the building . such a solution would be particularly appropriate for regions having strong sunlight . in this case , it would be advisable to provide a suspended cable for continuous feed from the battery . it would also be possible to combine such a system with conventional electrical supply , whereby an automatic device would switch over from solar power to mains supply when the sunlight drops below a predetermined threshold . it will be noted that the elevator according to the invention imposes no limit on height or speed of travel in respect of the counterweight . another form of the invention features a toroidal electric motor arranged to slide on a hollow cylindrical guide rail , reaching from the pit to the ceiling of the topmost storey , in so far as the travel and payload permit , meaning , in general , in residential buildings in which penthouse machinery is forbidden . the electrical system may also comprise regenerative braking , but the elevators should be provided with braking means usable when stopped and / or in emergency conditions . since the sheave used is not a drive sheave , it can play no part in such braking . hence , the simplest solution would be to install the braking system on the elevator car in order that it may act directly on the car guide rails , requiring a set of friction linings and an electro - magnet energized when the elevator is in motion . fig1 is an elevational view of an elevator system embodying the present invention , showing an elevator at an upper floor or landing ; and fig2 is a similar view , but of a system utilizing a different rope connection arrangement between the counterweight and the elevator cab . fig1 depicts elevator car 1 sliding on two guide rails 2 , suspended by rope 3 which runs over main sheave 4 and over deflecting sheave 5 , the other end of the rope consisting of a counterweight designated by generic reference 6 , arranged to slide along vertical guide rail 7 . according to the invention , sheaves 4 and 5 are idlers and have no drive function , such function devolving on linear electric induction motor 8 , which forms an integral part of counterweight 6 , and which cooperates with guide rail 7 , acting as an armature . as stated previously , guide rail 7 would with advantage be cylindrical and hollow , while motor 8 will be toroidal in shape and will surround guide rail 7 . linear motor 8 is fed by battery 9 , across an inverter 10 , which together form an integral part of counterweight 6 , alongside with battery charger 11 . as shown on the drawing , such charger 11 is fed from two separate sources , one from solar photocell panel 12 installed on roof deck 13 , to which charger 11 is connected by a flexible suspended cable 14 ; the other from mains supply system 15 , to which charger 11 is connected when counterweight 6 is stopped in bottom position , across socket connectors 16 . as stated above , braking of the car is ensured by device 17 , carried on car 1 , and cooperating with guide rail 2 of the car . in the variant shown in fig2 in which the components already described in connection with fig1 keep the same reference numbers , but suffixed by prime (&# 39 ;), sheave 4 &# 39 ; is installed in room 18 &# 39 ; designed for the purpose , so that it may be dimensioned as large as desired , which permits eliminating idler sheave 5 , thereby still further reducing wear on the sheave and on the rope . a feature of the elevator according to this invention is the additional advantage of being extremely silent . moreover , since in normal operation the braking system has no dynamic or regenerative action and since the use of the battery obviates sudden stops due to failure of the mains supply , wear on the friction lining is reduced and maintenance is lessened . in addition , since it is no longer necessary to observe the ratio between car weight and area in the usual types of electric elevators , the only condition imposed on the braking system is that it is capable of holding the car stopped in the event of overload thereof , in order to ensure the safety of the passengers . an elevator logic monitoring device -- determining direction of travel in response to a call from the car or from a landing , storing the calls , slow - down instruction , stop instruction or any other -- of known type , contained in a cabinet or decentralized into several parts , may be installed in some convenient location . to one skilled in the art , other modifications , variations and substitutions may be made to the described system , in whole or in part , without departing from the true scope and spirit of the invention .