Patent Description:
Wheel end assemblies are subject to a number of design constraints. Their diametric and longitudinal dimensions are limited by the size of wheel to be mounted to the hub end assembly and space to accommodate their longitudinal length can be limited by overall vehicle packaging factors. These size constraints can result in limited load carrying capacity and a limited capacity to transmit and generate torque at the hub. The size, power and configuration of motor integrated into or connected to the electric wheel end assembly can also place limits on the overall performance of the wheel and assembly.

<CIT> discloses a brake mechanism in combination with a planetary gearbox in which the brake mechanism resides within an inner portion of a fixed housing. Main wheel bearings are mounted on an outer part of the fixed housing.

<CIT> discloses a drive wheel system in which a central recess of a hub carrier has a compression spring and brake discs. A hub is mounted to the hub carrier by means of two tapered roller bearings.

There exists a need for improvement in wheel end assemblies.

The inventors have identified an advantageous architecture for an electric wheel end assembly, achieving a particularly beneficial combination of size, load capacity, and speed reduction/torque amplification. Further, an advantageous braking arrangement has also been identified by the inventors.

The electric wheel end assembly disclosed herein is particularly well adapted for use with a range of different motor models and sizes due to the architecture efficiently providing a large reduction ratio through its two stage planetary gearbox arrangement, along with a compact overall diameter, and the gearbox being disposed outside of the spindle arrangement such that the dimensions of input shaft and spindle can be relatively close to allow for a compact overall arrangement. An efficient means for packaging an input shaft braking arrangement within a spindle and/or mounting portion/mounting plate of the wheel end assembly has also been devised. Such a braking arrangement can allow for ease of maintenance and replacement/assembly of the braking arrangement in the electric wheel end.

According to one aspect of the present invention, there is provided an electric wheel-end assembly comprising:.

The wheel end assembly of the invention is particularly suited to providing a compact overall assembly and providing a suitable reduction ratio between motor and hub. An input shaft braking arrangement can efficiently provide a parking or service brake as an addition or as an alternative to a brake provided for more direct braking of the hub relative to the spindle.

The input shaft may comprise an outboard end connected to the input to the reduction gearbox. The input shaft may comprise a coupling sleeve. The input shaft may further comprise an outboard portion. The coupling sleeve may have an outboard end releasably coupled to the outboard portion of the input shaft within the spindle. The coupling sleeve may comprise an inboard end comprising the drive receiving portion arranged to connect to a drive shaft of an electric motor. The provision of a separate coupling sleeve in the spindle permits ease of assembly of the wheel end with a range of motor types without a need to change the design of the wheel end for each motor type.

The electric wheel-end assembly may further comprise at least one input shaft bearing disposed in a bore of the spindle, to rotatably support the outboard portion of the input shaft. The input shaft bearing may be disposed axially between inboard and outboard ends of the outboard portion. Such a bearing allows the outboard portion to be rotatably supported in the spindle while the coupling sleeve can be removed and replaced without disturbing the outboard portion of the input shaft.

The electric wheel-end assembly may further comprise an input shaft oil seal disposed in a bore of the spindle, axially between inboard and outboard ends of the outboard portion of the input shaft, and arranged to provide a seal between the outboard portion of the input shaft and the spindle. The oil seal acts to isolate the coupling sleeve from the wet parts of the gearbox, so that the coupling sleeve can be removed or replaced without unsealing the wet parts or disturbing seals.

At least one of the first and second stages may comprise axial thrust bearings arranged between the respective planetary gears and the respective planet carrier.

The thrust bearings can allow a stage to operate at high speed without undue wear, and so can extend the life of the gearbox. The thrust bearings are preferably provided on the first stage. This permits the first stage to operate at the necessary higher speeds and lower torques than the second stage, which operates at lower speed and higher torque.

The electric wheel-end assembly may further comprise one or more shims arranged between the axial thrust bearings and the respective planet carrier, the shims having a hardness greater than that of the planet carrier. The shims can further increase the durability of the gearbox.

The electric wheel-end assembly may further comprise a service brake arranged to apply a braking force to the hub with respect to the spindle.

The actuating means may comprise a biasing means arranged to bias the input brake toward an engaged position. An actuator may be arranged provide a force opposing the biasing means, to release the input brake. The input brake may be a normally-on type brake. The biasing means may be arranged within a piston of the actuating means. The actuating means may comprise an annular piston arranged about the input shaft.

The piston may be slidably received in a bore within the mounting portion or the spindle. The actuating means may further comprise a fluid chamber arranged to actuate the piston when pressure is applied within the fluid chamber, preferably to release the input shaft brake.

The input brake assembly and the inboard end of the spindle and mounting portion may be arranged so that the input braking assembly can be assembled by introducing components of the input braking assembly axially into a bore of the spindle from the inboard end. The components may be retained in place by a retainer component applied at the inboard end of the spindle and mounting portion.

Further features and advantages of the present invention will become apparent from the following description of embodiments thereof, presented by way of example only, and by reference to the drawings, in which:.

<FIG> illustrates a vehicle <NUM> into which an electric wheel end according to the present disclosure may be integrated. The vehicle has a cab <NUM> and may incorporate a cargo or passenger carrying region <NUM>. While <FIG> illustrates a cargo or passenger-carrying vehicle, the wheel-end of the present disclosure can be incorporated into any suitable type of vehicle requiring an electric wheel end assembly of the kind described herein. It can be desirable to drive such a vehicle from electric power sources. To achieve this, connection of individual electric motors to each wheel <NUM> the vehicle may be desirable. An electric wheel end assembly can be incorporated into one or more hubs <NUM>, <NUM>, <NUM> of the vehicle <NUM> in order to transmit drive from an electric motor to a wheel <NUM>. Electric wheel end assemblies can be incorporated into non-steerable wheels <NUM>, <NUM>. Alternatively, by incorporating an electric wheel end assembly as disclosed herein into a steering knuckle, it is possible to directly drive steerable wheels <NUM> from an electric motor connected to the wheel via an electric wheel end assembly as described herein.

<FIG> illustrates an example of an electric wheel end assembly <NUM> according to the present disclosure. The wheel end assembly <NUM> is arranged to transmit drive from an electric motor <NUM> to a hub <NUM>, via a gearbox <NUM>. The gearbox can reduce the rotational speed and increase the torque delivered to the hub <NUM>, as compared to that delivered directly from the output <NUM> of electric motor <NUM>.

Hub <NUM> is rotatably mounted to a spindle <NUM>. The hub <NUM> may be mounted to the spindle via one or more hub bearings <NUM>, <NUM>. The hub bearings may comprise an inboard hub bearing <NUM> and an outboard hub bearing <NUM>. The inboard and/or outboard hub bearings <NUM>, <NUM> may be mounted to the spindle <NUM> between an inboard end <NUM> of the spindle and an outboard end <NUM> of the spindle. In the present description, the terms inboard and outboard are used in a conventional manner with regard to vehicles and hub assemblies. Therefore, the wheel end assembly may have an outboard side <NUM> and an inboard side <NUM>. The inboard side <NUM> is nearer to a centreline of the vehicle to which the wheel end assembly is to be mounted, while the outboard side <NUM> is arranged further from the centreline of the vehicle, such that the outboard side <NUM> faces outwardly, away from the centreline.

At or toward its inboard end <NUM>, the spindle <NUM> is connected to a mounting portion <NUM>. Mounting portion <NUM> may take the form of a mounting plate. The spindle <NUM> may be connected to the mounting portion <NUM> in a removable manner, such as by being removably attached to the mounting plate via removable attachment means such as bolts, screws or rivets, or any other means of attachment which allows disassembly of the spindle from the mounting plate <NUM> in a repeatable manner without damage to the spindle or mounting portion/plate <NUM>. The spindle may alternatively be integrally formed with the mounting portion <NUM>, such as by being formed from a unitary piece of material with the mounting portion <NUM>, or by being permanently attached e.g. by welding or other permanent attachment methods, thereto.

An electric motor <NUM> may be mounted to the mounting portion <NUM>. The mounting portion <NUM> may comprise suitable surface features for engaging a body of the electric motor to prevent relative rotation between the electric motor <NUM> and the mounting portion <NUM>. The electric motor <NUM> may be secured to the mounting portion <NUM> by removable fixing means such as bolts. The electric motor may comprise an output shaft <NUM> for delivering an input torque to the input shaft <NUM>. The input shaft <NUM> can extend through a bore of the spindle <NUM> to transmit a rotational drive from the motor output at an inboard end of the spindle <NUM> to a gearbox <NUM> at an outboard end of the spindle <NUM>. The gearbox <NUM> comprises a plurality of gears arranged so as to provide a reduction ratio which reduces the rotational speed and increases the torque received from the end of <NUM>. The gearbox <NUM> may take any suitable form and in certain implementations a speed increasing gearbox may be implemented if desired. The gearbox <NUM> comprises a plurality of gears configured to mesh to provide the desired increase or reduction ratio between the input shaft <NUM> and the hub <NUM>. The illustrated embodiment shows a reduction gearbox.

The input shaft <NUM> therefore delivers a drive input from the motor output <NUM> to drive input <NUM> of the gearbox <NUM>. A drive output <NUM> of the gearbox can be connected to the hub <NUM> to deliver a rotational drive to the hub <NUM>. In the illustrated example, the drive output <NUM> is connected to, or may be integrally formed with, an end cap <NUM> of the hub <NUM>. The input shaft <NUM> is connected to the drive input <NUM> of the gearbox <NUM> at an outboard end <NUM> of the input shaft. The input shaft <NUM> may comprise an outboard portion <NUM>. At an inboard end <NUM>, the input shaft <NUM> may comprise a drive receiving portion <NUM> configured to engage with and receive a drive from the motor output <NUM>. The illustrated drive receiving portion comprises a bore arranged to receive a motor output shaft <NUM>. However, embodiments may be envisaged in which the drive receiving portion comprises a shaft projecting from the mounting portion <NUM> and configured to be received in a corresponding bore of an output of a motor <NUM>. These features permit the input shaft to receive a drive input from the electric motor <NUM>, to transmit that drive input through a bore of the spindle <NUM> the gearbox <NUM>. The input shaft <NUM> may be divided into two sections, and outboard portion <NUM> and a coupling sleeve <NUM>. The drive receiving portion <NUM> may be formed in the coupling sleeve <NUM>. The outboard portion <NUM> may comprise an inboard end <NUM>, which may be configured to engage an outboard end <NUM> of the coupling sleeve <NUM>. The outboard portion <NUM> and the coupling sleeve <NUM> may be engaged via a linearly slidable connection, for example a toothed connection, such as a spline. This enables the coupling sleeve <NUM> to be slid onto an end of the input shaft <NUM> within the spindle <NUM>, such that drive can be transmitted between the coupling sleeve <NUM> and the outboard portion <NUM>. This arrangement allows flexibility of the assembly, to receive a range of coupling sleeves, which can be configured to receive a range of motor types of different configurations and output configurations, for example.

The input shaft <NUM> may be rotatably supported within the spindle <NUM> by at least one input shaft bearing <NUM>. The input shaft bearing or bearings may be located between inboard and outboard ends of the input shaft <NUM>. In the illustrated embodiment one input shaft bearing is illustrated, however embodiments are envisaged in which a plurality of bearings, axially spaced along the length of the input shaft are implemented. An input shaft oil seal <NUM> may further be provided. The input shaft oil seal <NUM> may be located so as to provide a seal between the input shaft <NUM> and the bore of the spindle <NUM>. The input shaft oil seal <NUM> may be located so as to prevent oil flow from the gearbox <NUM> to the inboard end <NUM> of the input shaft <NUM>. Advantageously, the oil seal can be located on the outboard portion <NUM> of the input shaft. This can permit the integrity of the oil seal to be maintained while removing or replacing the coupling sleeve <NUM> and/or any components connected to it, such as the braking arrangement described later in relation to <FIG>.

The wheel end <NUM> of the present disclosure achieves a compact overall arrangement, combined with advantageous load bearing capacity and a higher reduction ratio than has previously been required of implemented in such a small overall envelope. Factors which contribute to this include the arrangement of the gear box and its gears outside of the end of the spindle <NUM>. In particular, the gearbox is arranged to an outboard side <NUM> of the hub bearing or bearings <NUM>, <NUM>. Only the input shaft and its bearing(s) <NUM> and/or oil seal <NUM> are located within the spindle <NUM>, allowing a small overall diameter to be achieved for the arrangement. In certain examples, the ratio of the outer diameter of the spindle to the outer diameter of the input shaft <NUM> is less than <NUM> to <NUM> and more preferably less than <NUM> to <NUM>, and may be <NUM> to <NUM> or less. These conditions are preferably met at the location on the spindle where the hub bearings are mounted to the spindle. Advantageously, a single input shaft passing through a bore of the spindle <NUM> can transfer a drive to the wheel end gearbox <NUM>, to permit a reduced diameter of spindle <NUM> as compared to other known arrangements.

Turning to the hub <NUM>, the hub may comprise a hub body <NUM>. The hub body may be mounted to the spindle via the one or more bearings <NUM>, <NUM>. The hub body may be connected to a hub casing <NUM>. The hub casing <NUM> may act as a casing for the gearbox <NUM>. A hub oil seal <NUM> may provide a seal between the hub <NUM> and the spindle <NUM>. As described above, the drive output <NUM> of the gearbox <NUM> may be transmitted to the end cap <NUM> of the hub <NUM>. Torque may be transmitted from the end cap <NUM> through the hub casing <NUM> to the hub body <NUM>. The torque may be transmitted to wheels attached to the hub by one or more wheel connection points <NUM>, which may take the form of the illustrated studs and nuts, or which may be implemented via other known wheel connection means, such as bolts fixed to suitable threaded holes in the hub body <NUM>, or other attachment means removably fixing a wheel to the hub.

A service brake <NUM> may be provided, to brake the hub <NUM> with respect to the spindle <NUM>. A brake rotor <NUM> may be provided and mounted in fixed relation to the hub <NUM>. In the illustrated example, the brake rotor <NUM> is a drum, although embodiments can be envisaged in which a dry disc brake or a wet disc brake is implemented, and in which the brake rotor <NUM> would take the form of a brake disc or a wet disc brake assembly. In the usual way for a drum brake, a friction member <NUM>, such as a brake shoe, may be mounted in non-rotating relation to the spindle <NUM>, so that the friction member <NUM> does not rotate about the axis of spindle <NUM>. Actuation means for actuating the friction member to engage the brake rotor can be provided in the usual way. In the case of a dry disc brake, the friction member(s) would be provided in the form of brake pads, which can be actuated to engage the brake disc. In the case of a wet disc brake, the friction members would be provided in the form of immersed friction discs fixed to the hub body <NUM>, which can be actuated to engage one or more non-rotating discs mounted into an additional carrier fixed on the spindle <NUM>. The wet disc brake product such as that currently sold under brand name Axletech™ W3H, W4H or W4R can be adapted for use in the arrangements described herein for the purpose of implementing a wet disc brake. The implementation of such disc or drum brakes will be readily understood by the skilled reader in light of the present disclosure and so are not described in detail herein for efficiency of the disclosure.

A ring gear support <NUM> may be provided, and can be retained in place on the spindle <NUM> by a retainer <NUM>, such as a threaded nut. The support <NUM> retains the ring gear <NUM> in fixed relation to the spindle <NUM>, such that torque can be transmitted through the gearbox <NUM> by engagement of gears of the gearbox with the ring gear <NUM>. The input shaft <NUM> may be rotatably supported in a bearing or bush <NUM> at or adjacent the outboard end <NUM> of the spindle <NUM>.

Details of the arrangement of the gears of the gearbox <NUM> will be explained in relation to <FIG> illustrates further details of an exemplary gearbox <NUM>, which may be implemented with the wheel end assembly disclosed in relation to <FIG>. Although embodiments in which alternative forms of gearbox are implemented can be envisaged, preferred examples include a planetary reduction gearbox. It can be advantageous to use a two-stage planetary reduction gearbox. A two-stage planetary reduction gearbox of the kind described in relation to the present disclosure can enable a particularly beneficial range of reduction ratios to be achieved within a compact size, whilst transmitting the desired level of torque.

In the example illustrated, the outboard portion <NUM> of the input shaft <NUM> is connected to the drive input member <NUM> of the gearbox <NUM>. The connection can be made at an outboard end <NUM> of the input shaft. The first stage <NUM> may comprise first stage planet gears <NUM> arranged to orbit the axis A of the gearbox relative to the spindle <NUM>. Ring gear <NUM> may be mounted in stationary relation to the spindle <NUM>. The drive input member <NUM> comprises a first stage sun gear <NUM>. The first stage sun gear <NUM> is arranged to engage first stage planet gears <NUM>, which also engage teeth of an outer ring gear <NUM>. Rotation of the first stage sun gear <NUM> causes the planet gears <NUM> to rotate in relation to the ring gear <NUM>, causing the first stage carrier <NUM> to rotate about the axis A of the gearbox <NUM>. The first stage planet gears <NUM> are arranged to rotate about first stage planet shafts <NUM>. First stage planet shafts <NUM> are mounted in the first stage carrier <NUM> and cause the first stage carrier <NUM> to rotate about the axis A when the sun gear of the first stage sun gear <NUM> causes the first stage planet gears <NUM> to rotate about their respective shafts <NUM>. The first stage carrier <NUM> can transmit torque from the input shaft <NUM> to the hub <NUM> of the wheel end assembly, which may preferably be transmitted via the second stage <NUM>.

A second stage planetary gearbox <NUM> may be provided. The output of the first stage carrier <NUM> may be connected to the drive input of the second stage <NUM>. Second stage <NUM> may comprise a second stage input member <NUM> comprising a sun gear. The second stage <NUM> may comprise second stage planet gears <NUM> arranged to orbit the axis A of the gearbox relative to the spindle <NUM>. The sun gear <NUM> of the second stage engages planet gears <NUM> of the second stage, which in turn engage ring gear <NUM>. Planet gears of the first and second stages may therefore engage a common ring gear <NUM>. The ring gear <NUM> may have a common pitch circle diameter for engagement with both the first stage planet gears <NUM> and the second stage planet gears <NUM>. Second stage planet gears <NUM> are arranged to rotate about second stage planet shafts <NUM>. Second stage planet shafts <NUM> are mounted in the second stage carrier <NUM> and may cause the second stage carrier <NUM> to rotate about the axis A when the sun gear of the second stage input member <NUM> causes the second stage planet gears <NUM> to rotate about their respective shafts <NUM>. The second stage carrier <NUM> can therefore transmit torque from the input shaft <NUM> to the hub <NUM> of the wheel end assembly. The second stage carrier <NUM> may be integrally formed with an end cap <NUM> of the hub <NUM>. The hub casing <NUM> may transmit torque between the hub body <NUM> and the end cap <NUM>.

It will be appreciated that alternative arrangements may be implemented in which the first stage <NUM> is omitted as a single stage planetary gearbox is implemented to transmit torque from the input shaft <NUM> the hub <NUM>. This will of course reduce the range of ratios available as compared to a two-stage planetary gearbox, but can reduce the axial length of the gearbox.

The input shaft may therefore directly drive the first stage where present, or directly drive the second stage illustrated, if the first stage <NUM> is omitted. The stage immediately connected to the input shaft <NUM> experiences the highest rotational speeds. In the illustrated gearbox, the first stage planet gears <NUM> are axially spaced from the first stage carrier <NUM> by thrust bearings <NUM>. This can enable the gearbox <NUM> to run with higher input speeds, which can result in higher output speeds whilst achieving the desired torque, by virtue of the high reduction ratio, which can be provided by the two-stage reduction gearbox. Shims <NUM> may be provided in between the first stage planet gears <NUM> and the first stage carrier <NUM>. The shims <NUM> may be provided in between the thrust bearings <NUM> and the first stage carrier <NUM>. These shims may be toughened or hardened as compared to the material of the first stage carrier <NUM>. This can be achieved by heat treatment or hardening treatments of the shims, or by choosing a material of a greater hardness than the material of the first stage carrier. This enables materials of suitable weight and structural properties to be selected for the first stage carrier, while the shims <NUM> can provide improved resistance to wear and heat generation for the higher speed first stage <NUM> of the gearbox <NUM>.

The first stage planet gears <NUM> may be mounted to the first stage planet shafts <NUM> by bushes or bearings <NUM>. Similarly, the second stage planet gears <NUM> may be mounted to 2nd stage planet shafts <NUM> via bushes or bearings <NUM>.

To facilitate assembly of the first stage drive input member <NUM> to the input shaft <NUM>, a removable attachment means such as a bolt <NUM> may be provided to retain the drive input member <NUM> to the input shaft <NUM>.

<FIG> shows an enlarged cross-section of an input braking assembly <NUM> which may be incorporated into the wheel end assembly <NUM> of the present disclosure. The input braking assembly <NUM> may be at least partly received in the spindle <NUM>, preferably within a bore within the spindle <NUM>. The input braking assembly <NUM> may be at least partly received in the mounting portion <NUM>. As described previously, and seen in greater detail in <FIG>, the spindle <NUM> can in some embodiments be integrally formed with mounting plate <NUM>, or may be a separate component to the mounting plate <NUM>. In use, an electric motor <NUM> can be mounted to the mounting portion <NUM> and a drive input from its output <NUM> can be applied to the drive receiving portion <NUM> of the coupling sleeve <NUM>. The coupling sleeve <NUM> may in certain embodiments be integrally formed with the outboard portion <NUM> of input shaft <NUM>. However, having a separately formed coupling sleeve <NUM> can allow the coupling sleeve to be easily replaced without a need to interfere with the remainder of the wheel-end assembly, which improves the flexibility of the wheel end arrangement for use with different motor types and also facilitates maintenance and replacement of the wheel end assembly and/or motor.

The input braking assembly <NUM> provides a means for braking the input shaft <NUM> with respect to the spindle. When considered in conjunction with the optional service brake <NUM> described in relation to <FIG>, it will be appreciated that the wheel end assembly may therefore comprise a plurality of braking mechanisms <NUM>, <NUM>. A first braking mechanism may be a service brake <NUM> arranged to directly brake the hub <NUM> with respect to the spindle <NUM>. Such a brake being in direct communication with the hub and <NUM> and mounted to the spindle <NUM> can provide a relatively high braking force to provide sufficient braking torque for use in service, such as to bring a vehicle to a stop during normal operation. Therefore, if power assistance is available during use of the vehicle for such a service brake, then direct braking of hub <NUM> can be achieved. On the other hand, it may be desirable to have a brake <NUM>, which can be actuated with a relatively low actuation force. This may be of particular use when the vehicle is not in use and power assistance is not available, for example as a parking brake. By applying a parking brake at an input shaft of the wheel end assembly, the braking force at the input shaft, and its corresponding braking torque, are amplified through the ratio of the gearbox before reaching the hub <NUM> and so a braking assembly having a lower braking force and lower braking torque at the input shaft can be of benefit for braking the hub <NUM>. This can be particularly beneficial when implemented as a parking brake for a vehicle. Alternatively, the input braking assembly <NUM> may be implemented without the service brake <NUM>. The input braking assembly can be used as both a parking brake and a service brake. When used as a service brake, the brake may be actively actuated with a piston arranged to provide positive pressure to actuate the braking assembly, either as an alternative to or in addition to the "normally on" arrangement described in more detail below.

The input braking assembly <NUM> may comprise one or more static braking members <NUM>. In this context, the term static is intended to mean non-rotating. However, the static braking members <NUM> may not be completely static with respect to the spindle <NUM>, since it is preferable that they are able to move axially with respect to the spindle <NUM> and the input shaft <NUM> in order to provide for the axial actuation and the release of the braking assembly <NUM>, by compression and release of the braking members <NUM>, <NUM>. The one or more static braking members <NUM> can be arranged to engage movable braking members <NUM>. Movable braking members <NUM> are mounted to the input shaft <NUM>. They may be mounted to the input shaft <NUM> at the coupling sleeve <NUM>. The movable braking members <NUM> may be attached to the input shaft <NUM> so as to permit them to move axially with respect to the input shaft <NUM>, while being held in a fixed rotational configuration with respect to the input shaft <NUM>. This can be achieved by attaching them via a spline arrangement. This axial freedom of movement can enable the movable braking members <NUM> to be axially compressed against static braking members <NUM> when the brake is activated. Frictional engagement between the movable <NUM> and static <NUM> braking members therefore provides a braking force to the input shaft <NUM> with respect to the spindle <NUM>.

An actuating means <NUM> is provided to actuate the input shaft braking assembly <NUM>. The actuating means <NUM> is preferably arranged to apply an axial compressive force to the static and movable braking members <NUM> and <NUM>. The actuation means <NUM> may comprise a biasing means <NUM>, such as spring. The biasing means <NUM> may bias the input braking assembly to an engaged or disengaged configuration. In the illustrated arrangement, the biasing means <NUM> is configured to provide an axially compressive force toward the braking members <NUM>, <NUM> to bias the input braking assembly to an engaged configuration. This arrangement can be considered a "normally on" brake. A further actuating means can be provided to counteract the actuating force of the biasing means <NUM>. Such further actuating means can be arranged to provide an opposing force to the biasing means <NUM>. In the illustrated embodiment, a piston arrangement is illustrated. A chamber <NUM> is provided, which, when provided with an actuating pressure, can provide an axial force in an opposite direction to biasing means <NUM>. In the particular example illustrated, by providing pressure to chamber <NUM>, preferably via a pressure inlet <NUM>, the piston <NUM>, which may be annular, is biased away from the braking members <NUM> and <NUM> to place the braking arrangement in a disengaged configuration. A first seal <NUM> and a second seal <NUM> may be located at either side of chamber <NUM> to avoid leakage of pressurised fluid from the chamber, particularly when pressurised during actuation. It is possible to operate the input braking arrangement <NUM> as a service brake in the 'normally on' arrangement described, by controlling the pressure in opposite relation to the required braking force. In such an arrangement, the pressure provided to the piston is reduced as an increased braking force is required. When no pressure is provided, the brake is at maximum braking force and when sufficient pressure is provided to overcome the biasing means <NUM>, then no braking force is provided to compress the braking members <NUM>. A normally on braking arrangement can therefore be provided at the input shaft, which may be arranged to be used as a service brake.

In certain embodiments, such as in the illustrated example, the movable braking members may be mounted to the coupling sleeve <NUM>, whereas in others they may be mounted to the input shaft <NUM>. Mounting the braking members to the coupling sleeve further facilitates maintenance of the overall arrangement. When maintenance of the parking brake is required, the coupling sleeve and related braking members can be removed without significant disturbance to the remaining parts of the wheel end assembly, as described earlier. In certain embodiments, the piston <NUM> may be received in the mounting portion <NUM>, while the movable braking members and static braking members may be received in the spindle <NUM>. Oppositely oriented arrangements can be envisaged, in which the piston <NUM> may be disposed in the spindle and the braking members <NUM>, <NUM> are arranged in the mounting portion <NUM>. Therefore, some or all of the braking assembly may be received in the spindle and some or all of the braking assembly may be received in the mounting portion <NUM>. A retainer component <NUM> may be provided to retain the components of the input braking assembly <NUM> within the bore of the spindle <NUM>. The retainer component <NUM> may act as a fixed component against which biasing means <NUM> may react to bias the piston <NUM> toward the braking members <NUM> and <NUM>. Retainer component <NUM> may be provided as a cover plate, arranged to cover the components of the input braking assembly <NUM> and retain them within a bore of the spindle <NUM> and/or mounting portion <NUM>.

Electric wheel end assemblies are therefore disclosed having optimised architectures, which can enable a compact product that is able to carry high loads and transmit high torques. The relative configuration and ease of access to the input shaft enables the end assembly of the present disclosure to be highly adaptable to different input electric motors and also facilitates easy maintenance of such motors and their replacement. The novel braking arrangements described herein further enable efficient provision of suitable braking of the wheel end hub by efficient means, which are also well configured for ease of assembly and maintenance.

Claim 1:
An electric wheel-end assembly (<NUM>) comprising:
a mounting portion (<NUM>);
a spindle (<NUM>) having an inboard end (<NUM>) connected to the mounting portion and an outboard end (<NUM>) distal from the mounting portion;
a hub (<NUM>), rotatably mounted to the spindle via one or more hub bearings (<NUM>, <NUM>) disposed between the inboard and outboard ends of the spindle;
a <NUM>-stage planetary reduction gearbox (<NUM>) disposed at the distal end of the spindle and comprising:
a drive input (<NUM>) and a drive output (<NUM>);
a first planetary stage (<NUM>) comprising a first sun gear (<NUM>) and a plurality of first planet gears (<NUM>) rotatably mounted to a first stage planet carrier (<NUM>);
a second planetary stage (<NUM>), comprising a second sun gear (<NUM>), and a plurality of second planet gears (<NUM>) rotatably mounted to a second stage planet carrier (<NUM>);
the first stage planet carrier being connected to the sun gear of the second stage;
an input shaft (<NUM>) comprising an inboard end (<NUM>) having a drive receiving portion (<NUM>) arranged to releasably connect to a drive shaft (<NUM>) of an electric motor (<NUM>), the input shaft extending through the spindle to deliver a rotational input from the drive receiving portion to the drive input of the reduction gearbox, the drive output (<NUM>) of the reduction gearbox being connected to the hub, to drive the hub in rotation about the spindle;
an input shaft braking arrangement (<NUM>) disposed at least partially within the spindle and arranged to brake the input shaft with respect to the spindle;
wherein a ratio of an outer diameter of the spindle to an outer diameter of the input shaft at a location where the one or more hub bearings are mounted to the spindle is less than <NUM> to <NUM>.