Abstract: The invention relates to a drive device for a rotary anode of an X-ray tube having a drive motor with a stator (10) and a rotor (15; 21) which drives the rotary anode, the stator (10) and the rotor (15; 21) being separated by a gap and the stator (10) having slots (11) whose circumferential length (17) has been dimensioned for driving a bipolar X-ray tube. In order to enable a more universal use of such a drive device the stator (10), which has been dimensioned for driving the bipolar X-ray tube, is also used for driving a unipolar X-ray tube, the diameter of the rotor (21) and thus the gap (22) being dimensioned in such a manner that the efficiency or the torque of the drive device lies within a maximum range (II).

Abstract: A linear accelerator x-ray target assembly including an electron beam which contacts an x-ray target and generates x-rays. The target is mounted such that it can rotate freely about its axis. The target has a contoured axially outer edge. Fluid flow impinging the contoured axially outer edge of the target acts to impart rotary motion on the target. The fluid flow helps to dissipate heat from the target in two ways. Firstly, heat is transferred to a cooling fluid as the cooling fluid passes over the target. Secondly, the rotation of the target helps to dissipate heat from the target by distributing the electron beam contact point around the target instead of having the electron beam impact continuously on one spot on the target.

Abstract: An anode (16), (16') and a cathode (14), (14') are mounted in an evacuated envelope (12), (12') of an x-ray tube (10). One of the anode and cathode is rotatably mounted on bearings (20), (20') relative to the evacuated envelope. In the embodiment in which the anode is rotatably mounted relative to the evacuated housing, a rolling ring assembly (40) provides a current path from the anode through the evacuated housing to ground without the current path passing through the bearing (20). In this manner, pitting and other damage to the bearing due to arcing is eliminated. In the embodiment in which the cathode is rotatably mounted relative to the evacuated envelope, the anode and envelope rotate as the cathode is held stationary (58, 60). A plurality of rolling ring assemblies (40'.sub.1, 40'.sub.2, . . . ) provide electrical communication between electrical control circuitry disposed outside the rotating housing and the cathode assembly (14').

Abstract: X-radiator with an X-ray tube with a vacuum housing to which an anode and a cathode are firmly connected, has a coolant container that surrounds the X-ray tube and is filled with a coolant, and a radiation protection housing that surrounds the coolant container. The X-ray tube and the coolant container are rotatably seated relative to the radiation protection housing, with the drive of the X-ray tube and/or the coolant container operating such that the X-ray tube and the coolant container rotate around a rotational axis during operation of the X-radiator. An electron beam deflection system that is stationary with respect to the radiation protection housing is arranged inside the radiation protection housing.

Abstract: The invention relates to a rotary-anode X-ray tube comprising a plain bearing, notably a spiral groove bearing, which comprises a bearing shaft and a bearing shell which encloses the bearing shaft, contains essentially molybdenum and/or tungsten or alloys thereof, and consists of at least two bearing shell portions, a liquid lubricant being present between the bearing shaft and the bearing shell. The material consumption and the manufacturing effort for the bearing shell are reduced in that on the outer side of the bearing portions there are provided connection elements which consist of a weldable material, and that the connection elements are connected to one another by way of a welded joint.

Abstract: An improved anode assembly for an x-ray tube is described herein. The assembly includes:(a) a target having a central cavity formed therein;(b) a tubular stem for connection to the target to form a target/stem assembly;(c) an insert within the central cavity, shaped to receive a portion of the stem, and comprising a niobium-based alloy; and(d) a rotor body assembly adapted for connection to the target/stem assembly and rotation therewith.X-ray tubes which incorporate such an anode assembly are also described, as are methods for bonding a target to a tubular stem for use in a rotating x-ray tube.

Abstract: An X-ray tube has a vacuum housing, on which is provided a high-voltage terminal connected to the anode. An electrical damping resistor, through which the tube current flows and which is connected between the high-voltage terminal and the anode, is arranged within the vacuum housing. This resistor can be constructed as a component through which the tube current flows, and which connects the anode plate with its mount, such as a rotor in case of a rotating anode X-ray tube. The component has a low electrical conchannelivity so that the connection of the anode plate with the mount has a resistance of at least 250 ohms and at most 15 kiloohms.

Abstract: In an X-ray tomographic apparatus, while rotating a gantry rotary section around a region where an object to be photographed is placed, the anode target of an X-ray tube is rotated at a predetermined high rotation rate and X-rays are emitted from the anode target. In emitting the X-rays, the rotation torque is increased to be larger than that prior to rotation of the gantry rotary section in accordance with the rotation drive power supplied to a stator coil. A decrease in rotation rate of the anode target of the X-ray tube can be prevented even during rotation of the gantry rotary section, radiation at a necessary and sufficient X-ray dose can be assured, and an X-ray tomographic image can be properly obtained.

Abstract: In a rotating anode X-ray tube of this invention, a liquid metal lubricant supplied to bearing portions between a rotary member and a stationary member for instructing rotation of the rotary member is to be filled to a volume having a range of lower limit being an amount to fill bearing gaps, including helical grooves, and as an upper limit being 70% of the capacity of the interior in which the lubricant can flow, measured from the end portion of a helical groove slide bearing portion closest to the interior of a vacuum container. In the rotating anode X-ray tube, leakage of the liquid metal lubricant can be prevented, and a stable bearing operation can be maintained.

Abstract: A efficient point source x-ray target tape assemble. A tape is wrapped helically around a rotating drum a little more than one complete turn so as to create an overlap section where a section of the tape is positioned parallel and adjacent to a separate section of the tape. The tape advances slowly across the outside surface of the drum at a speed which is a small fraction of the tangential surface speed of said drum. In a preferred embodiment a pulsed laser beam is focused on the tape at a fixed spot in space through which the tape moves in order to create x-rays from plasma generated by very high intensity ablation of the tape material. The combination of the drum rotation and the tape advancement across the surface of the drum permits substantially full utilization of the tape material for generation of x-rays.

Abstract: An X-ray tube of a rotating anode type for reducing acoustic noise and vibration by using an isolating structure which suppresses and prevents transmission of the vibrational energy from the rotating anode assembly to a vacuum envelope and a housing of the X-ray tube. The isolating structure comprises at least one flexible member which is connected between a support structure of the the anode assembly and a neck portion of the vacuum envelope forming a hermetical sealing therewith, and symmetrically disposed isolating members placed between the neck and head portions of the vacuum envelope and the housing, respectively. The flexible members of the isolating structure can be incorporated into the walls of the vacuum envelope.

Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved target/stem connection wherein at least about 40,000 x-ray scan-seconds are accomplished prior to tube failure due to anode assembly imbalance comprising a metallic target and a metal stem bonded to provide a composite rotating x-ray tube target is disclosed. An insert of an alloy, for example, tantalum alloy, is placed between the target layer and the stem and then bonded thereto to produce a composite x-ray tube target/stem having a high remelt temperature and bond strength which retains its balance throughout the manufacturing process and during x-ray tube operations is also disclosed.

Abstract: In a computed tomography apparatus having a gantry, on which a rotating anode x-ray tube and a radiation detector are disposed, the gantry being rotatable around a system axis and being tiltable relative to an axis extending perpendicularly to the system axis, the direction of rotation of the gantry is opposite the direction of rotation of the rotating anode in the x-ray tube. Gyroscopic forces acting on the bearing of the rotating anode are thereby at least partially cancelled, significantly reducing mechanical stress on the anode bearing.

Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved target/stem assembly comprising a metallic target and a large bore, thin-walled tubular metal stem which, when connected to a rotor body assembly, provides a rotating x-ray tube anode assembly is disclosed. An insert of an alloy, for example, tantalum alloy, is placed between the target layer and the large bore, thin-walled tubular stem and then bonded thereto to produce a composite x-ray tube target/stem assembly. The target/stem assembly is then connected to a rotor body assembly by fasteners, preferably threaded, applied through a plate connected to the tubular stem and preferably through a thermal washer to produce a rotating anode assembly having high bond strength that provides acceptable balance during x-ray tube operations.

Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved target/stem connection and a coating, operatively positioned between the target and the stem, for enhancing the diffusion therebetween to reduce tube failure due to anode assembly imbalance comprising a metallic target and a metal stem bonded to provide a composite rotating x-ray tube target is disclosed. An insert of an alloy, for example, titanium alloy, is placed between the target layer, the stem and a coating, operatively positioned between the target and the stem, for enhancing the diffusion therebetween and then bonded thereto to produce a composite x-ray tube target/stem having a high remelt temperature and bond strength which retains its balance throughout the manufacturing process and during x-ray tube operations is also disclosed.

Abstract: An x-ray tube has an anode whose target area is divided into regions formed of different materials, whereby focal spots of different size can be optionally generated in each of the regions. The focal spots belonging to one region are respectively generated at different locations but all focal spots are generated so close together that the focal position is essentially the same for all focal spots. An operating method for such an x-ray tube is also disclosed.

Abstract: An x-ray tube, in addition to an anode and a cathode arrangement, has first and second electrodes that are located in an evacuated housing provided with a beam exit window. The anode and the first electrode are at potentials that are positive in comparison to the potentials of the cathode arrangement and the second electrode. Further, the first and the second electrode are arranged lying opposite one another such that secondary electrons emanating from the anode must pass through the space located between the first and the second electrode in order to proceed to the beam exit window. These secondary electrons are thus substantially all prevented from reaching the beam exit window, thereby avoiding excessive heating of the beam exit window.

Abstract: In an X-ray tube apparatus of a rotating anode type, a stator surrounds an anode rotary structure and an insulating container section placed around the outer periphery of a stationary structure such that a portion of its coil conductor located near the anode target side constitutes an expanding flared coil conductor portion. Therefore, it is possible, for the X-ray tube equipped with an envelope having a large-diameter metal section and small-diameter insulating container section, to shorten the axial length from an anode target of the X-ray tube to a far end of the rotary structure and to suppress the build-up of electric charges on the inner surface of the insulating container section.

Abstract: Apparatus equipped for both megavoltage radiotherapy and a diagnostic X-ray source for portal imaging. Both the high energy therapeutic and low energy diagnostic source of radiation are physically located at the same point in apparatus space, and utilize a single moveable target converter that is physically positioned according to the desired use, either therapy or diagnostics.

Abstract: A mounting part for mounting an end of an axle on a projection of a housing, such as an axle in a vacuum-tight housing of a rotatable anode, is characterized by a sleeve section which can have radial play during assembly and engages a clamp arrangement to remove the radial play at the end of assembly of the section on either the end of the axle or the projection of the housing. The clamp arrangement is a bevel provided on the member being telescopically received in the section or on a ring which is telescopically received on the member being received in the section.

Abstract: An X-ray tube construction of the rotating anode type for reducing acoustic noise and vibration by using granules which are placed loosely within an anode cavity formed between the outer surface of an anode shank and a wall of an anode sleeve in proximity to a bearing journaled to a rotor shaft for rotation of an anode structure.

Abstract: The motor efficiency of a rotating X-ray tube having an anode assembly and a cathode assembly, can be greatly improved. The improved efficiency x-ray tube motor comprises a stator and rotor assembly having an air gap between the stator and rotor. The improved efficiency is achieved by reducing the air gap. The stator is operated at anode potential and electrically connected through an anode high voltage cable.

Abstract: An X-ray tube of the rotary anode type including lubricant passages or lubricant housing recesses formed opening at those areas of a fixed or rotary structure where spiral grooves of slide bearings are present so as to allow lubricant to be more reliably supplied to these grooves-provided areas. Even when the rotary structure starts its rotation or it is being rotated, therefore, the liquid metal lubricant can be more reliably interposed between those faces of the fixed and rotary structures on which the slide bearings are formed. This can prevent the bearings from being damaged and the operation of these bearings can be kept more stable.

Abstract: An X-ray tube of the rotary anode type includes a rotary structure to which an anode target is fixed, a stationary structure fitted into the rotating member, slide bearings arranged between them and provided with spiral grooves, and a lubricant consisting of gallium alloy and supplied to the slide bearings. The rotary structure includes a first rotating member to which the anode target is connected and a second rotating member provided with the bearings. These first and second rotating members are kept coaxial to each other and connected together at their those portions which are remote from the anode target when viewed in the rotating axis direction of the target and along a heat transmitting line extending from the target to the bearings, but heat insulating clearances and are formed between the rotating members at their other portions not connected. The first rotating member is made of one of those materials which have a heat conductivity smaller than 0.1 (cal/cm.sec..degree.C.) at temperature range of 0.

Abstract: The invention is directed to a bearing for the rotating anode of an x-ray tube comprising at least one rolling bearing suitable for absorbing axial forces which is loaded with an axially directed force for suppressing the bearing play. Magnets are provided which generate the axially directed force in non-contacting fashion.

Abstract: A ferrofluidic seal arrangement for sealing a high-speed rotary shaft which passes between an environment at atmospheric or high pressure and an environment at high-vacuum is provided, which is especially useful in a high-speed rotating anode apparatus for generating x-rays in a CAT Scan apparatus or the like. A differentially-pumped region between a multi-stage ferrofluidic seal and a single-stage seal insures that no seal bursting into the high-vacuum region occurs. Bearings supporting the shaft are arranged in a mechanically-stable arrangement but are isolated from the high-vacuum environment. Thus, neither the high-vacuum environment nor the differentially-pumped region need be continually mechanically pumped, and a relatively light-weight apparatus results.

Abstract: An anode assembly (14) is mounted by a bearing assembly (20-28) in a bearing housing (30). The bearing housing is constructed of substantially pure copper or other high thermal conductivity metal. The bearing housing defines a shoulder portion (36) between a side wall (34) and a mounting shank (38). The mounting shank is threaded (66) to be clamped into a mounting assembly (60) which provides substantially the sole support for the bearing and anode assembly. A steel reinforcing collar (52) with an integral seat portion (54) supports the shank and shoulder portions of the bearing housing. A vacuum envelope (40) of the x-ray tube includes a metal cap portion (44) which is sealed between the seat and shoulder portions in a vacuum tight relationship.

Abstract: Noise is reduced in an X-ray tube by inserting a non-glass insert between sections of the glass vacuum tube. The non-glass insert has an impedance which is significantly different than the impedance of the glass tube sections. This impedance mismatch inhibits vibration energy from passing from one glass section to the other. In addition to having a different impedance than the glass sections, the non-glass insert can be made of a heavier material, thus presenting sufficient mass to dissipate vibration energy. The non-glass insert is connected to the glass sections by a pair of connecting members, each of which has a coefficient of thermal expansion closely matching that of the glass sections. Each connecting member has a ring with an annular flange extending perpendicularly therefrom. The ring of each connecting member is attached a respective one of the glass sections and each flange is attached to the insert.

Abstract: An X-ray analysis apparatus has a charged particle beam generator, an X-ray generating target bombarded by the beam and a detector for X-rays from said target transmitted by a test piece. To improve the spatial resolution of the apparatus, the beam size is reduced at the target by locating the target outside a vacuum chamber of the beam generator by providing the target as a non-circular narrow track of X-ray generating material exposed at both surfaces of the target, and by providing the beam generator with a beam accelerator and means for reducing the beam diameter between the beam accelerator and the target.

Abstract: An X-ray tube anode which is composed of a refractory metal having a focal track thereon with the refractory metal including tantalum, hafnium, zirconium and carbon in a minor amount and molybdenum in a major amount. The anode has improved high temperature properties and fabricability. It can be utilized alone or in combination with the usual graphite portion.

Abstract: A rotary X-ray tube of the anode type wherein a jacket which serves to prevent lubricant from being scattered into the space in a vacuum envelope is attached to at least one of a rotary structure to which an anode target is fixed and a stationary structure for holding the rotating body, enclosing a clearance opening which forms a border relative to the space in the vacuum envelope.

Abstract: A rotary anode x-ray tube includes a vacuum vessel in which a cathode, an anode target, a connecting rod, a rotor, bearings, and a heat conducting plate are arranged. The cathode electrode emits electrons. The anode target generates x-rays when electrons emitted from the cathode electrode collide with the target. The connecting rod supports the anode target. The connecting rod is constituted by a rod member consisting of a pulverized sintered material. The rotor is mounted on the connecting rod. The anode target is rotatably supported by the bearings. The heat conducting plate is arranged between the anode target and the rotor. A heat conducting plate made of a material having excellent heat conduction characteristics can be arranged between the anode target and the rotor. The connecting rod is manufactured by processes such as plasticization including tube spinning.

Abstract: An X-ray tube for greatly enhancing the output of photons relative to a standard tube includes a source of an electron beam focused on a target at an angle of approximately 10.degree. to produce high energy photons emitted at an angle along their centerline of 5.degree. to 15.degree., both angles referring to the surface of the target. Reduction of impurgement of scattered electrons on the tube window is affected in various ways such as use of a magnet to deflect electrons from the photon stream or locating the window out of alignment with the most intense scattered electrons. Scattered electrons are also absorbed by an essentially zero albedo shield disposed in the path of the majority of the scattered electrons not directed at the window.

Abstract: In X-ray tubes with a rotating anode, the shielding of the stator is obtained by a first conductive layer that is deposited on the external wall of an insulating bell-shaped part and has an electrical discontinuity, and by a second conductive layer that is deposited on the internal wall of an insulating cup-shaped or bowl-shaped part, the bell and the bowl encasing the stator and thus creating an electrostatic screen against the high frequency oscillations that result from the "crackling" of the tube. The device can be applied to X-ray tubes for radiology instruments.

Abstract: A rotary X-ray tube of the anode type wherein at least one of bearing surfaces which are partly formed on rotary and stationary structures is made of ceramics whose main component is the nitride, boride or carbide of at least one of those deviation metals, except chromium, which belong to a group IVA, VA or VIA element of a period 4, 5 or 6 of the Periodic Table.

Abstract: An improved high performance x-ray tube having a rotating graphite anode therein and method of preparation thereof. The surface of a graphite anode body is oxidized in air for removing the surface damage caused during the machining of the anode body. The anode body is provided with a diffusion barrier layer of rhenium contiguously disposed on the substantially damage free surface of the anode body. An anode target layer is then deposited on top of the barrier layer.

Abstract: An x-ray tube construction comprising a housing and a shaft assembly mounted within the housing for rotational movement within the housing. An anode target is provided in the housing. A three-ball mounting is provided for mounting the anode target on the shaft assembly so that the anode target rotates with the shaft assembly. A cathode is disposed within the housing in the vicinity of the anode target. A voltage supply is connected to the anode target and to the cathode for accelerating electrons from the cathode to impinge upon the anode target to create x-rays. The three-ball mounting serves to minimize the transfer of heat from anode target to the shaft assembly. A motor drive is coupled to the shaft assembly for rotating the shaft assembly and the anode target carried thereby. A heat cage is disposed within the housing and surrounds the anode target. The heat cage has a window therein to permit the x-rays to pass therethrough.

Abstract: An improved high performance x-ray tube rotating having a graphite anode therein and method of preparation thereof. A graphite anode body is provided with a microcracked contiguously disposed diffusion barrier layer of rhenium on the surface of the anode body. An anode target layer is then deposited on top of the barrier layer.

Abstract: An x-ray radiator has an elongated cathode for emitting an electron beam having an elongated cross section, the electrons of the electron beam being accelerated onto an anode for generating x-radiation. The cathode is formed by a geometrical member completely filled with electron-emitting material, and the material of the cathode contains at least one element from the group of rare earths and at least one element from the group of precious metals or boron.

Abstract: In an X-ray tube having a stationary anode stem, a shaft joined to the tube anode, and a rotary bearing to support the shaft and anode for rotation relative to the stem, a preloading element is positioned in a bore formed in the stem and is axially displaceable to apply a selected preload to the bearing. The preloading element has a cylindrical outer surface provided with longitudinal spaced-apart grooves in parallel relationship with the bore axis. A locking ball positioned in each groove extends through a complementary hole formed through the stem to oppose rotational displacement of the preloading element with respect to the stem, while allowing axial displacement to take place. An annular retaining ring positioned around the anode stem engages the locking balls to urge them in toward the bore, and to oppose radial displacement of the preloading element.

Abstract: An improved metal center rotating anode x-ray tube is shown. The improved x-ray tube includes means for preventing the build-up of charge on the anode glass portion of the tube envelope where the glass flares by constraining the equipotential lines of the electric field in the vicinity of th eflare to parallel the flare surface. Parallelism may be achieved by (1) controlling the angle of the flare and sealing the flare directly to the metal section, (2) modifying the anode rotor to include a flare conforming to the glass flare, and (3) including a ground plane screen in the tube housing.

Abstract: An X-ray tube for greatly enhancing the output of photons relative to a standard tube includes a source of an electron beam focused on a target at an angle of approximately 10.degree. to produce high energy photons emitted at an angle along their centerline of 5.degree. to 15.degree., both angles referring to the surface of the target. Reduction of impurgement of scattered electrons on the tube window is affected in various ways such as use of a magnet to deflect electrons from the photon stream or locating the window out of alignment with the most intense scattered electrons. Scattered electrons are also absorbed by an essentially zero albedo shield disposed in the path of the majority of the scattered electrons not directed at the window.

Abstract: The apparatus is an anode for an X-ray tube which is rotated at high speeds during operation. The anode include a plate of refractory material with high mechanical strength. On both faces of the plate are fixed two blocks of light weight refractory material. One of the blocks is formed of several sub-blocks fixed to one another through brazing. A layer of X-ray emitting mattering is deposited on the outer surface of these sub-blocks.

Abstract: A rotating x-ray tube includes an electron-beam accelerator assembly having an indirectly heated cathode structure. The cathode structure includes an electron-emitting region mounted at the center of a rotationally symmetric Pierce-cathode configuration. An electron beam travels along a selected path as the tube rotates so that the electron beam strikes selected portions of a target mounted within the tube as it rotates. Two magnetic coils and a ferromagnetic mirror plate are arranged to function as a single quadrupole electromagnet, which has its axis parallel to and offset from the electron beam and which elongates the electron beam in a radial direction.

Abstract: An X-ray rotary anode (1) comprising a graphite carrier body (3) and a tungsten target layer (11) can withstand a high-temperature load when an intermediate layer is provided which is composed of a layer of silicon carbide (7) and a layer of titanium nitride (9).

Abstract: A magnetic coupling for a device, such as a cathode, which is received in a vacuum bulb of a tube which has shafts for mounting the tube for rotation on an axis, has an inner ferromagnetic part disposed in the vacuum bulb and connected to the device and an outer ferromagnetic part which is arranged outside of the vacuum bulb and aligned with the inner part. The outer part comprises a magnetic arrangement having a plurality of pole pieces to which the poles of a ferromagnetic yoke that forms the inner part are allocated.

Abstract: The invention relates to a rotary-anode X-ray tube comprising a sleeve bearing, notably a helical-groove bearing, for journalling the rotary anode in the axial direction, which bearing comprises at least two pairs of bearing surfaces for taking up axial forces acting in opposite directions, each pair comprising two bearing surfaces which are present on bearing portions which are rotatable with respect to one another and which bearing surfaces cooperate via a lubricant, the helical-groove bearing communicating with the vacuum space of the X-ray tube via at least opening. Because at the area between the pairs of bearing surfaces there is provided a lubricant reservoir which communicates with the lubricant in the pairs of bearing surfaces and in the stationary bearing portion there is provided a duct which connects the lubricant reservoir to the vacuum space of the X-ray tube, it is achieved that the bearing will not be damaged in the case of loss of lubricant.

Abstract: The invention relates to an X-ray tube used to obtain radiological images in which sharpness and contrast are improved. To this end, the X-ray tube has an anode consisting, at least partially, of a massive layer made of an X-ray emitting material in which at least one hollow part demarcates a surface exposed to a beam of electrons.

Abstract: An x-ray diagnostics generator which includes a rotating anode x-ray tube includes circuitry for setting the speed of rotation of the anode dependent on exposure parameters. At particular rotational speeds, the motor bearing for the rotating anode is subject to mechanical resonances, causing vibrations which can damage the bearing. A vibration detector is provided in mechanical contact with the x-ray tube, and when vibrations due to such mechanical resonances are sensed, a signal is provided from the detector to a processor which automatically slightly alters the rotational speed.

Abstract: A rotating x-ray tube has a vacuum housing provided with central shafts at both sides, which are rotatably held in bearings connected to a radiator housing. An anode is rigidly mounted to the vacuum housing, and a cathode arrangement, having an eccentrically disposed cathode, is mounted on one of the shafts. The shaft supporting the cathode arrangement is hollow, and a filament transformer is disposed on the hollow shaft. A further shaft, which is rigidly connected to the cathode arrangement, is conducted through the hollow shaft. The cathode arrangement and/or the interior shaft are rotatably connected to the hollow shaft. The secondary coil of the filament transformer, which is connected to the glow helices of the cathode arrangement, is mounted on the interior shaft.