Abstract: An electric motor with a thermal safety feature has a rotor having a rotor winding, a brush for a current transmission to the rotor winding, a case which receives the brush, a switch-off contact which is arranged relative to the case so that it is contacted in response to a thermally caused position change of the case.

Abstract: Disclosed are methods of making dynamoelectric machines which include use of two sheet metal cup-shaped members to form a housing that completely surrounds and encloses the stator. The stator is assembled with a can in such a manner that the core of the stator is completely contained within the can. Thereafter, a cap is positioned at the exposed face of the stator and the cap and can are joined together by a sheet metal fastening technique which displaces material from one superposed sheet into a second sheet of material. The can and cap are precision formed so that they will have precision sized and located bearing receivers and core retention regions. Both the cap and the can are provided with multiple flange locations which are utilized for fastening the can and cap together during the assembly process.

Abstract: In order to reduce the wear on the brushes (6) and thus extend the operating lives of the brushes and of the commutator motor, brush sparking on the trailing edges (6.2) of the brushes (6) is reduced a commutation magnetic field (M), produced for example by an additional magnet (4) placed axially behind the brushes (6), such that the magnetic field (M) deflects the moving charge carriers in the brushes (6), to thereby reduce the current density at the trailing edges (6.2) of the brushes (6).

Abstract: An improvement to an electric fuel pump which includes an electric motor with a rotating commutator defining an axial direction, a radial direction and a tangential direction, and having a circumferential surface, and a carbon brush having a contact surface contacting the circumferential surface of the commutator. The brush includes a gap extending from the contact surface in a radial direction and further extending through the brush in the axial direction, the gap reducing flotation of the carbon brush caused by a layer of fuel drawn between the carbon brush and the commutator. In an alternate embodiment, the brush includes a pressure relief hole extending from the contact surface completely through the brush in the radial direction.

Abstract: A manual electric machine tool (10), having an electric motor (16), whose commutator (20) can be connected to a voltage source via at least one carbon brush (22) pressed against the commutator (20) by spring means (26), wherein the carbon brush (22) includes a head part (34) and a foot part (35) and has an electric pigtail lead (40) and a turn-off device (38), which at a certain wear of the foot part (35) of the carbon brush (22) automatically disconnects the electrical connection between the voltage source and the commutator (20), gains a longer useful life between service intervals for changing carbon brushes in that the carbon brush (22) is lengthened in the region of its head part (34) by a single axial continuation (36), which serves as a socket for the turn-off device (38) and is dimensioned such that the spring (26) enter flush and integrally into the outer contour of the carbon brush (22) between the outermost outer edges of the head part (34) and of the continuation (36), inside these outer edges.

Abstract: An electric motor with a sensor, in particular an rpm sensor, is proposed. The sensor contains at least one means (20), generating a magnetic field, as the signal emitter, at least one magnetic field sensor (28, 30) as the signal receiver, and signal conducting means (22, 24, 26). The signal conducting means (22, 24, 26) contain magnetically conducting material and conduct the signal of the at least one magnetic field-generating means (20) to the at least one magnetic field sensor (28, 30). At least one current conducting means (40, 42, 44) is arranged essentially along the signal conducting means (22, 24, 26).

Abstract: In order to reduce its size of a coil-rotation type electromagnetic clutch in an axial direction and to prolong the life of its brush, a sliding current supply mechanism, which has slip rings and slidable brushes which contact the slip rings, is located inside an inner circumference of a housing boss of a compressor. The current is supplied to an electromagnetic coil via the sliding current supply mechanism. Since the sliding current supply mechanism is located in the boss, a current supply passage is formed without increasing the size of the clutch in axial direction. Thus the installation of the electromagnetic clutch in the engine room is facilitated. Furthermore, since the sliding current supply mechanism is located near the rotational center of the clutch, the life of the brush is prolonged due to the small peripheral velocity of the brush.

Abstract: An electric rotating machine has an armature coil comprising outer and inner coil trunks disposed in slots of an armature core as well as outer and inner coil arms disposed along an axial side surface of the armature core. The outer coil arms are arranged to operate as a commutator and in slidable contact with brushes. The diameters of the radially outermost parts of the outer coil arms and the brushes are larger than that of the radially outermost surface of the outer conductor. This arrangement assures a larger commutator-brush contact area that reduces current density as well as heat generation in the commutator-brush contact area. As the radially outwardly extending parts of the outer coil arms are exposed to the surrounding air, the outer coil trunk, the outer coil arm and the brushes as well as the radially outwardly extending part are cooled effectively during rotation of the armature core.

Abstract: An improved method for the manufacture of a compact brush guide holder assembly which is commonly found on machines in which electricity is to be transferred between an electrically conductive brush element as it moves and makes contact with a rotatable conductor such as a commutator. The brush holder assembly constructed of material that reduces antifrictional forces having a guiding channel or chamber defined by upper and lower curvilinear surface for supporting the electrically conductive brush element which receives compressed tension from a fixed non-removable constant force spring which is composed of a beam uncoiled section in addition to a coiled section having integrally fixed mounted Teflon bushings that are free to ride and float horizontally and vertically on mounting post that pass through its center.

Abstract: A brush holder plate includes plugs with a blade terminal and an extension connected thereto. The plugs with their extension are inserted from below into the brush holder plate which is provided with sleeves on its top surface. The extension is passed through the sleeve, and a strand is slipped from the other side into the sleeve. An electrical connection between the strand and the plug is produced by pinching the sleeve, on the one hand, and the plug is fixed mechanically on the brush holder plate, on the other hand.

Abstract: A slip ring amplifier has a rotor fixedly mountable on a rotatable tubular member and carrying an amplifier mounted in a recess connected to a sensor fixedly mountable on the rotatable member. A stationarily mounted stator is coupled to the rotor by bearings. A slip ring brush block with leaf contacts is mounted in a cavity between the rotor and the stator. End caps are mounted on opposite ends of the rotor and the stator and fixed to one of the rotor and stator. Labyrinth seals are disposed between each end cap and the stator. In one embodiment, an electrolytic fluid fills the cavity between the rotor and stator and surrounds the brush block and leaf contacts. In another embodiment, a dielectric coating is provided on the leaf contacts. Conductors extend from the leaf contacts through the stator to a connector fixedly mounted on the stator.

Abstract: Disclosed is an improvement to the stability of D.C. motor brushes mounted in brush boxes with wings is improved by angling the wings toward the commutator such that the brush spring contacts the brush at one or more points intermediate the ends of the brush. Improved cooling is provided by utilizing an end plate with apertures and a brush plate which in combination with the commutator, provides a brush plate aperture for cooling air flow. In a preferred embodiment, speed variations of the motor can be achieved by selectively disconnecting one or more brushes in a four brush embodiment reducing the torque and rotating speed of the motor. In a preferred embodiment, the use of a diode to interconnect same polarity brushes permits a speed change to be accomplished by selectively connecting one or the other end of the diode.

Abstract: A commutator is disclosed which is adapted to be mounted on a rotor shaft of an electric motor for cooperation with electrical contacts of the motor, the commutator being capable of accommodating two speeds of the motor. The commutator includes a support member formed of electrically insulating material and having a central opening for receiving the rotor shaft, the support member having a surface portion for attachment of commutator segments. A first plurality of circumferentially spaced, electrically conductive commutator segments are attached to the surface portion of the support member and are arranged in a generally circular array and wired to the armature to accommodate at least a first speed of the motor. A second plurality of circumferentially spaced, electrically conductive commutator segments are attached to the surface portion of the support member and are positioned radially outward of the first plurality of spaced commutator segments.

Abstract: The invention describes a carbon brush for an electrical machine. Carbon brushes of this type need to fulfill two requirements. First, the carbon brush should be as resistant to abrasion as possible. Second, as little noise as possible should be generated at the brush/collector crossover during the operation of the motor. Consequently, the invention proposes to bevel the face surface of the carbon brush, and to provide the face surface with transverse grooves within its lower region.

Abstract: In an ordinary DC motor in a windshield wiper, operating speed tends to increase as the motor brushes become seated. The invention counteracts this tendency by providing a brush geometry which causes the effective angular position of a brush to change during seating. The change is in a direction which tends to reduce speed.

Abstract: A resilient thin sheet is used for a brush instead of a conventional brush unit which includes coil springs, pig tails and graphite brushes. A slip ring is made of perforated copper which is impregnated with carbon powder. The brush has two arc-shaped arms extending along the circumference of the slip ring and contacting portions disposed at the edges of the arms which are in contact with the peripheral surfaces of the slip ring. Wear resistant members are welded or caulked to the contacting portions to prevent excessive wear of the brush, thereby increasing the life of the brush.

Abstract: This invention relates to a carbon brush for an electric motor. These carbon brushes are guided in tubular brush holders and are pressed against a commutator. Furthermore, the brushes of the present invention include inclined side edges so that the front frontal surface has a trapezoidal cross-section. The consequence thereof is that, when sliding along the commutator, the commutator bars will always support the side edges over the major part of their length. The ratchet effect is thus suppressed.

Abstract: A grounding system for an AC or DC motor or other rotating apparatus comprising a conductive brush in resilient contact with a contamination-free conductive member removably secured onto a rotating part such as a motor shaft or tachometer shaft. The contacting surface is preferably formed of brass and is shielded from contamination from motor bearings and the like, for reliably shunting the shaft to the frame of the machine so as to avoid high voltage transients across bearings as would otherwise result in bearing damage or destruction. A brush housing or holding means positions the brush in juxtaposition with the rotating conductive member and cooperates to substantially enclose the region of contact between the brush and the conductive member.

Abstract: The invention provides a brush cartridge for a commutator-type motor. The brush cartridge includes a housing that is made of an electrically conductive material and that has an integrally formed terminal so that the cartridge can be plugged into a circuit without the need for wiring. The brush cartridge also includes a brush supported in the housing for sliding movement relative thereto and a spring member for biasing the brush into engagement with a commutator on the motor when the cartridge is installed. The brush cartridge also includes a flexible shunt connected between the housing and the brush. The shunt limits the range of sliding movement of the brush to permanently retain the brush in the housing.

Abstract: A brush assembly for an electric motor comprises a brush for making sliding contact with a commutator, the brush being fitted to an end of an elongate resilient electrically conductive brush arm fixed to a brush mounting plate. The brush and brush arm are arranged to ensure that the brush contacts the commutator at a single point in the vicinity of a side face of the brush so that the resilient urgings of the brush arm causing the brush to bear on the commutator surface creates a lateral twist in the elongate brush arm.

Abstract: The present invention provides a damping member constituted of a viscoelastic member and a constraint member, each of which is formed on a brush made of thin metal plate, in a dc minimotor, the viscoelastic member comprising adhesive mass containing a copolymer of alkyl acrylate and acrylic acid. The present invention further provides a brush constituted of the above damping member and a dc minimotor equipped with the brush.

Abstract: A brush holder embodies certain generic features that render it suitable for use in numerous brush card assemblies. The brush holder has sidewalls that provide guidance of an associated brush, and integral locators for locating an associated spring strip for urging the brush toward a commutator. A brush holder may be formed singly, or multiple brush holders may be integrally formed and joined by an integral bus bar.

Abstract: An improved brush assembly is provided for conducting electrical power from a fixed power system to a rotating ice protection system. The invention is especially adapted for use with an aircraft propeller ice protection system. According to an aspect of the invention, the brush assembly has a housing with a brush enclosure, the enclosure having slots provided therein for slidably receiving a plurality of brushes. A plurality of wear inserts are disposed in the slots adjacent the brushes in order to provide a wearing surface to prevent excessive wear of the brushes.

Abstract: A slip ring unit which comprises self-lubricated carbonaceous rings and a wear resistive brush made of laminated-elastic-copper-alloy-sheets are used to supply a field current to a field coil which is carried by a rotor of an alternator. Therefore, the space for accommodating the brush and slip ring unit of the alternator is made compact and the alternator size can be made small.

Abstract: A brush structure for a motor is provided for realizing an equalization of wear of brushes without causing an early wear of a specific brush while not necessitating a complicated conduction controlling device. A first brush, which is one of four brushes, conducted at both Lo mode and Me mode is formed to have a larger sliding contact area for contacting a commutator slidably compared with a sliding contact area of a second brush which is conducted at Hi mode only. Current density in the first brush at Lo mode and Me mode becomes smaller than current density at Hi mode.

Abstract: A DC motor brush assembly includes a brush brought into contact with a commutator piece which is connected to the coil of a DC motor, and a brush holder of plastic material for holding the brush against the motor housing. The brush is formed by bending from a bottom shield sheet. The bottom shield sheet is brought into intimate contact with a mold to form a non-molding chamber containing the brush when the brush holder is to be insert-molded. The brush holder is molded integrally over the bottom shield sheet.

Abstract: An electrical brush having a wear indicator in the form of a marking substance within the brush which removes a film from a rotating collector surface of an electrical device just prior to the brush becoming worn to its minimum length. The removal of the film leaves a bright streak on the collector surface, and provides a visual indication that the brush is in need of replacement.

Abstract: A brush wear sensor for a dynamoelectric machine having a rotating commutator and brushes which contact the commutator detects movement of the brush a predetermined distance inwardly which indicates excessive wear of the brush. The brush wear sensor is normally electrically isolated from the brush and from the brush holder in which the brush is mounted. When excessive brush wear occurs, the brush wear sensor contacts the spring which moves the brush as it wears and urges the brush into contact with the commutator. The brush wear sensor is then electrically connected to the brush holder and the brush, providing an indication that the brush has moved the predetermined distance inwardly. The brush wear sensor allows the detection of excessive brush wear without disassembling and visually inspecting the brushes.

Abstract: In a multi-pole electric motor, the terminal pieces of same polarities are placed adjacent to each other while the terminal pieces of different polarities are placed remote from each other, and the terminal pieces of common polarities are connected by shunt tabs which can be selectively cut apart. For instance, when a four-pole electric motor is to be used as a one-speed motor, the shunt tabs connected across associated terminal pieces are not cut apart, and the terminal pieces are appropriately connected to external power lines. When the motor is to be used as a two-speed motor, the shunt tabs connected across associated terminal pieces are cut apart, and the terminal pieces are appropriately connected to external power lines. Thus, the electric motor can be readily adapted either as a one-speed motor or a two-speed motor by using standardized component parts. Furthermore, even when the motor should overheat, there would be no short-circuiting, and the reliability of the motor can be improved.

Abstract: A liquid pump has a DC motor and a pump in a cylindrical casing. A pair of brushes are slidably contacted with a commutator of an armature while being biased by springs. The specific resistance of the positive brush is lower than the specific resistance of the negative brush to enable the voltage drop at the brushes to be decreased and motor efficiency to be increased without increasing commutator wearing speed. The biasing force provided by the spring biasing the positive brush is lower than the biasing force provided by the spring biasing the negative brush.

Abstract: A brush adapted to effect contact between an elastic metallic support and an electrical track which presents insulating parts and conducting parts. Said brush takes a form similar to that of a tip of a ball-point pen, with a metallic contact ball which is crimped in a metallic receiving shaft.

Abstract: In an armature of a starter motor, commutator bars are formed by bending one end portions of upper layer armature conductors toward the inner circumferential side in the radial direction along an axial end surface of an armature core. A brush which slidably contacts commutator bars is constructed in a multi-layered type comprised of two kinds of brush materials each having different specific resistance layered in a rotational direction of the armature.

Abstract: An electric motor including a housing defining an aperture therethrough is disclosed. The motor also includes an armature mounted in the housing and a brush mounted in the housing and slidably connected to the armature. The housing substantially encloses the armature and the brush. The aperture is positioned with respect to the brush so that the brush may be visible through the aperture and so that the remaining usable life of the brush may be visually determined while the electric motor is assembled.

Abstract: The process comprising the charging into a mould (3) of at least one electrically conductive powder (4), the compression by means of a piston (5) of the contents of the mould to form a crude brush (7), the heat treatment of said crude brush (7) as well as the fixing of the ends of the electrical conductors (2), characterised in that the charging involves at least the simultaneous introduction of at least two conductive powders (4B, 4A and/or 4C . . . ) for obtaining a brush formed by integral blocks (1B, 1A and/or 1C . . . ), the junction (1AB and/or 1BC . . . ) between said blocks being orientated at least in part in the compression direction (13).

Abstract: A permanent magnet type motor comprising:a field magnet including permanent magnet arranged inside a yoke in an 8-pole structure; andan armature including an armature coil and armature core, the armature coil and the armature core arranged inside the field magnet through an air gap;wherein the field magnet has a pole arc set in a range from 31.degree. to 37.degree., and wherein the length (lm) of main poles in an axial direction is set with respect to the length (Lc) of the armature core in the axial direction so as to satisfy the inequality of 1.0<Lm/Lc<1.4.

Abstract: A terminal connector in an electric motor permits easy and smooth connection between a brush terminal and a power terminal by installing a case cover to a case frame. A support plate fixed to the case cover is divided into a terminal portion provided with a power terminal and an output shaft portion disposed on the output shaft side. The terminal portion is supported so that it is movable with respect to the output shaft portion. During assembly the terminal portion is movable to assure connection between the brush terminal and the power terminal.

Abstract: A brush holder apparatus and method for biasing a brush outwardly of a brush box. A brush box cover is slidingly disposed over an electrical cable along with a coil spring. Next, a brush shunt is electrically secured to an end portion of the electrical cable by a crimp member. The brush box cover is then slidably urged towards a brush secured at a terminal end of the brush shunt. This causes the brush shunt to be folded so as to place it in general longitudinal alignment and parallel with the electrical cable. The brush box cover is then further slid along the electrical cable, thus urging the spring over the brush shunt and into engagement with the brush electrically secured at the terminal (i.e., outer) end portion of the brush shunt. The brush box cover is further slid along the electrical cable until the crimp member and a portion of the brush shunt become wedgingly engaged in a portion of the brush box cover, to thereby hold the spring in a compressed condition between the brush box cover and the brush.

Abstract: A carbon brush holder for a commutator motor which a carbon brush is replaceably installed in and which can facilitate assembling of the carbon brush holder and the carbon brush, and easily dissipate heat produced from the carbon brush, enhancing the function of the carbon brush. The carbon brush holder for a commutator motor used for as a housing of a carbon brush connected to a brush terminal via a flexible copper conductor reduces frictional contacts of side surfaces of the carbon brush and inside surfaces of the brush holder body which has no cartridge-formed conductive insert, and prohibits electric short phenomena therebetween. Thus, the generation of heat is reduced.

Abstract: Each of the two brush leafs of an electric motor comprises a first resiliently flexible conductive section, attached to a terminal, and an additional resiliently flexible section extending an acute angle to the first section. The first and second ends of the first section are disposed on opposite sides of a contact portion of the additional section which engages a commutator forming part of the motor. It is therefore possible to increase the length of the first section to thereby provide robust brush leafs which are nevertheless capable of flexing sufficiently to accommodate discrepancies in the mounting of the brush leaf means and in concentricity of the commutator.

Abstract: An improved homopolar machine in which a solid sliding current collector, or brush, is provided for contact with a flat, annular contact surface of a rotor. The flat plane of the contact surface is orthogonal to the rotor's axis of rotation. A plurality of such contact surfaces with corresponding brushes may be employed. Also, several means for actuating the brush into contact with the rotor contact surface are provided.

Abstract: The provision of an electric rotating machine which can reduce the mechanical and thermal loads applied thereto. Coil arms and coil trunks are provided in roughly parallel orientation to the end faces of an armature core only through insulating rings and insulating spacers. Metal brush is disposed on coil arms, whereby the overall length of the armature can be remarkably shortened. In addition, a commutator, conventionally necessary, can be eliminated, whereby the length of the production process for the armature can be reduced. Moreover, in an arrangement where projections of the upper coil arm are fit in holes of the insulating spacer, as the displacement of the upper coil arm towards the outer periphery is regulated, the length of the axial protrusions of the upper coil arm from the end face of the armature core can be minimized.

Abstract: A multi-speed, direct current motor (120) incorporates a high speed (24) brush disposed between the low speed (22) and the common ground (26) brushes and having a non-arcuate end face (25) which, unlike the conventional arcuate brush end face (23,27), is not subject to speed-drift erosion. The non-arcuate end face (25) is configured of two offset surfaces (55,65 & 57,67) which intersect to provide a line of contact (43) between the end face (25) of the high speed brush (24) and the commutator (40) which is displaced from the center line of the high speed brush (24) in a direction counter to the direction of rotation of the motor, that is toward the leading edge (21) of the brush (24). The intersecting surfaces (55,65 & 57,67) may comprise either flat planar surfaces or contoured surfaces.

Abstract: A homopolar dynamoelectric machine comprises a solenoid coil for generating a magnetic field, having a cavity formed around an axis thereof. A rotating shaft, which constitutes a rotor, is rotatably provided in the cavity about the axis. A circular plate, which also constitutes the rotor, is integrally fixed on the shaft. A rotating body is rotatably supported by the plate about an axis of the shaft. A first electric current path, through which an electric current can pass from a proximal portion to a distal portion of the rotor, is integrally provided in, for example, the plate. A second electric current path, through which an electric current can pass from a distal portion to a proximal portion of the rotor, is integrally provided in the rotating body. The first and second paths are electrically connected in series, and are adapted to be electrically connected to a power supply in order to supply a direct current to these paths.

Abstract: Methods and apparatus to reduce wear on surfaces in sliding contact by inducing vibratory movement in one or more of the surfaces. The movement is substantially perpendicular to a plane of contact between the surfaces and substantially nonuniform across the area of contact. The nonuniform vibratory motion of one surface with respect to another results in small rotational vibration of one surface with respect to another even as contact is maintained between the surfaces. Rotational motions tend to decrease surface wear due to thermal mounding by moving the zone of actual contact with time; rotational motions also open temporary gaps between the surfaces which allow the escape of wear particles, thus decreasing subsequent abrasive wear. The invention may be applied to sliding electrical contacts, either linear or rotating, and to sliding frictional contacts, as in brakes and clutches.

Abstract: A brush device includes elliptic compression coil springs, an electrical conductive member, rotary shaft, and brushes pushed against an electrical conductive member on the rotary shaft with the elliptic compression coil springs. And the outer end parts of each of the elliptic compression coil springs are bent inwardly of the ellipse formed by the elliptic compression coil spring.

Abstract: A single speed, two pole permanent magnet motor has compact brush card assembly mounted within the volume form by a plurality of ring shaped laminations forming the armature to allow the height of the motor to much less than a standard motor. In addition, there is shown a two speed, four pole permanent magnet motor having a height much less than a standard two speed motor. In each motor there are electrically connected to the supply lines a choke means and across each supply line is a capacitor for suppressing radio frequency interference.

Abstract: An electrical machine having a stator formed from a pair of cup-shaped permanent magnets symmetrically disposed on opposite sides of a conductive, disk-shaped rotor. The magnets are polarized such that a portion of their external magnetic flux passes in one direction through a short peripheral gap formed by the magnets in which the periphery of the rotor is disposed. The remainder of the external magnetic flux substantially passes in the opposite direction through a cavity defined by the inner volume of the cup-shaped magnets. The inner portion of the disk-shaped rotor is disposed in this cavity. One embodiment of the invention implements the cup-shaped magnets with modified "magic spheres" mounted on either side of the conductive disk-shaped rotor. Other embodiments use a magnetic plate on one side of the disk-shaped rotor to act as a magnetic mirror for a cup-shaped magnet mounted on the other side of the rotor.

Abstract: A pair of hollow permanent magnets mounted to form a toroidal stator having cylindrical gaps and opposed cavities. The magnets are polarized such that their magnetic flux passes in one direction through the gaps to intersect the rotor along two cylindrical bands and then passes through the magnetic shell and subsequently in the opposite direction through the cavities to intersect the rotor in a cylindrical region located between the cylindrical bands. An electrical circuit couples a utilization device to the rotor. Another embodiment of the invention uses a magnetic mirror to replace one of the permanent magnets. Still other embodiments teach the use of a plurality of toroidal stators mounted in tandem about a common rotor. The machine may be used as a homopolar generator or a homopolar motor.

Abstract: Core-type brushes used in dynamoelectric machines, such as electric motors, have cores which are arranged in substantially parallel planes extending at an angle with respect to the direction at which the brushes move toward the commutator as the brushes wear. As the brushes wear, the position of the cores relative to the outer surface of the commutator changes, preventing constant positioning of the cores relative to the commutator surface and reducing or preventing non-uniform commutator wear which occurs when the cores maintain a fixed position with respect to the commutator surface as the brushes wear. This arrangement of the cores eliminates the need to resurface the commutator at brush change, reduces the time required to properly seat the brushes to the commutator and increases commutator and brush life.

Abstract: A brush assembly for an electric motor has a brush 20, a brush terminal 30 and a brush spring 40. The brush spring is fashioned from an elongate strip 41 of resilient, electrically conductive material and is fixed to the brush terminal at its ends to form a loop with an intermediate portion fixed to the brush to electrically connect the brush to the brush terminal and to urge the brush into contact with a commutator of the motor. Brush guiding arrangements for guiding the brush to the commutator has a guide pin 51 fixed at one end 52 to the brush terminal and co-operating with a guide hole 21 formed in the brush to define the position of the brush on the commutator 11.