Vacuum cleaner arrangement

An arrangement including: a handheld suction unit in combination with an elongate suction wand to form a stick-vac cleaner, the arrangement further including a wall-mountable docking station for supporting the stick-vac cleaner on a wall in an upright, docked position when not in use. The arrangement provides for relatively stable storage of the stick-vac cleaner in the upright position, convenient for use.

REFERENCE TO RELATED APPLICATIONS

This application claims the priority of United Kingdom Application No. 1004149.9, filed 12 Mar. 2010, and of United Kingdom Application No. 1014423.6, filed 31 Aug. 2010, the entire contents each of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of vacuum cleaners, and more specifically to ‘stick-vac’ cleaners of the type generally comprising a handheld suction unit connected to a floor tool by an elongate suction wand.

BACKGROUND OF THE INVENTION

Broadly speaking, there are four types of vacuum cleaner: “upright” vacuum cleaners, “cylinder” cleaners (also referred to as “canister” cleaners), “handheld” vacuum cleaners and “stick” vacuum cleaners, the latter being popularly referred to as “stick-vac” cleaners, or simply “stick-vacs”.

Upright cleaners and cylinder cleaners are well known. They tend to be mains-operated and are used for relatively heavy-duty cleaning applications.

Handheld vacuum cleaners are relatively small, highly portable vacuum cleaners, best suited to relatively low duty applications such as spot cleaning floors and upholstery in the home, interior cleaning of cars and boats etc. Unlike upright cleaners and cylinder cleaners, they are designed to be carried in the hand during use, and tend to be battery-operated.

Stick-vac cleaners essentially offer a lightweight, functional alternative to upright cleaners for relatively low duty floor-cleaning applications, such as cleaning up floor spills.

Broadly speaking, there are two types of stick-vacs. The first type is, in a sense, an ultra slim-line upright cleaner, though usually “cordless” rather than mains-operated. An example of this type of stick-vac cleaner is shown in UK Patent Application No. GB2377880A1, in this case additionally incorporating a removable, handheld vacuum-cleaning unit. Stick-vacs of this first type may be free-standing; otherwise, they tend to be stored simply by leaning the stick-vac against a wall when not in use (in the manner of a long-handle brush or broom).

The second type of stick-vac cleaner is a spin-off from the handheld vacuum cleaner, and comprises a handheld suction unit which is carried in the hand in the same way as a handheld vacuum cleaner, but in combination with a rigid, elongate suction wand which effectively reaches down to the floor so that the user may remain standing while cleaning a floor surface. A floor tool is typically attached to the end of the rigid, elongate suction wand, or alternatively may be integrated with the bottom end of the wand. Designs of this type of stick-vac cleaner are shown in U.S. D298875, U.S. D303173 and U.S. D280033. In each case, the handheld suction unit incorporates the motor, the fan and some sort of separating apparatus, which may be a bag or a cyclonic separation system.

Stick-vac cleaners of the second type are predominantly multi-mode, hybrid machines: in such cases, the wand is removable and the handheld suction unit may then be used independently as a handheld vacuum cleaner, as desired. However, this is not an essential feature of these types of stick-vac cleaners and it is conceivable that the wand may be permanently attached to the handheld suction unit.

A feature which distinguishes stick-vacs of the second type from stick-vacs of the first type is that the first type is “bottom heavy”—the motor is located low down in similar manner to a full-sized upright cleaner—whereas the second type is “top heavy”—the use of a handheld suction unit in combination with an elongate suction wand means that the motor (being inside the handheld suction unit) is located nearer the top end of the machine.

The “top heavy” distribution of weight in stick-vacs of the second type means that they are not particularly convenient to store in stick-vac mode. If the stick-vac cleaner is leaned against a wall in an upright position with the floor tool supported on the floor and the handheld suction unit resting against the wall, the relative weight of the handheld suction unit tends to make the stick-vac cleaner as a whole unstable. On the other hand, if the stick-vac cleaner is turned upside down and leaned against the wall with the relatively heavy handheld vacuum cleaner supported on the floor, the relatively dirty lower end of the cleaner will consequently rest against the wall, which is undesirable. Also, when the stick-vac cleaner is stored in an upside down position rather than an upright position, the natural inclination is to grasp the stick-vac cleaner in the region of the relatively dirty lower end of the stick-vac cleaner in order to turn the cleaner back round to the upright position for use.

Consequently, conventional stick-vac cleaners of the second type often tend to be stored on the floor or, where there is insufficient space to do so, tend to be partly disassembled for storage after use and then reassembled again when it is desired to use the machine in stick-vac mode. The need for disassembly and reassembly in particular discourages use of the machine in stick-vac mode.

SUMMARY OF THE INVENTION

According to the present invention, there is provided an arrangement comprising: a handheld suction unit in combination with an elongate suction wand to form a stick-vac cleaner, the arrangement further comprising a wall-mountable docking station for supporting the stick-vac cleaner on a wall in an upright, docked position when not in use.

By “upright position” is meant a position in which the elongate suction wand extends downwardly from the handheld suction unit towards the floor. Storing the stick-vac cleaner in the upright position has the advantage that a user may conveniently grasp the hand held vacuum cleaner in order to disengage the stick-vac from the docking station, at which point the stick-vac is ready for use in the upright position: there is no tendency for the user to grasp the relatively dirty, lower end of the stick-vac in order to manipulate the stick-vac cleaner into the upright position for use. At the same time, the “top heavy” stick-vac cleaner is advantageously supported in a relatively stable, upright position by the docking station (which laterally supports the stick-vac cleaner in the upright position).

In a particularly stable arrangement, the docking station is arranged releasably to lock the stick-vac in the upright, docked position i.e. so that the stick-vac cleaner is essentially fixed relative to the docking station in the upright, docked position.

The docking station may be arranged for engaging the handheld suction unit in order directly to support the hand held suction unit when the stick-vac cleaner is in the upright, docked position. Consequently, because the center of mass is dictated largely by the position of motor, which is inside the handheld suction unit, the center of mass of the stick-vac cleaner will be relatively near to the point of support on the wall; this provides a particularly stable upright, docked position, and results in relatively low stresses on the docking station components.

The handheld cleaner may be a battery-powered handheld cleaner, in which case it may incorporate a set of exterior charging contacts connected to an onboard rechargeable battery, and the docking station may comprise a respective set of charging contacts for connection to a mains supply, the charging contacts on the docking station being arranged for engagement with said exterior charging contacts on the handheld cleaner to form a battery-charging circuit when the stick-vac cleaner is in the upright, docked position. Thus, the docking station advantageously charges the battery onboard the handheld unit when the stick-vac cleaner is in the upright, docked position.

The charging contacts on the handheld suction unit may be arranged in any suitable manner. In some cases, it may be desirable to arrange the contacts on the handheld suction unit in a way which means that the contacts face upwards when the stick-vac cleaner is in the upright position.

If the charging contacts on the handheld suction unit are arranged so that they face upwards when the stick-vac cleaner is in the upright position, it has been found that there can be a tendency for the charging contacts to pull away from the respective contacts on the docking station, under the weight of the stick-vac cleaner. To address this problem, the charging contacts on the docking station may be spring-biased for urging the charging contacts downwardly into engagement with said upward-facing charging contacts on the handheld suction unit.

The docking station may comprise a catch for engaging the handheld suction unit part to secure the stick-vac cleaner in the upright, docked position, the catch being arranged to hold the charging contacts on the handheld suction unit in engagement with the charging contacts on the docking station. Thus, reliable contact is ensured for charging the battery when the stick-vac cleaner is in the upright, docked position.

The catch may be spring-loaded for urging the charging contacts on the handheld suction unit into engagement with the charging contacts on the docking station. This may be in addition to, or alternative to, the charging contacts on the docking station being spring-loaded as mentioned above.

The docking station may comprise an opposing pair of clamping members, at least one of the clamping members being resiliently biased towards the other clamping member for resiliently clamping the stick-vac against the other clamping member to lock the stick-vac in the upright, docked position. This provides a particularly stable arrangement, wherein the stick-vac is clamped securely in the upright, docked position.

Furthermore, docking and release of the cleaner is essentially one-handed, as described in more detail below.

The pair of clamping members may consist of a lower clamping member arranged for clamping upwardly against a respective lower part of the handheld suction unit and an opposing, upper clamping member arranged for clamping downwardly against a respective upper part of the handheld suction unit. This has the advantage that the clamping load on the cleaner is in direct opposition to the force of gravity.

In a particular arrangement, the lower clamping member is fixed in use, relative to the wall, and the upper clamping member is resiliently biased downwards towards the lower clamping member.

The clamping members may be arranged for relative sliding movement along a clamp axis to engage the stick-vac, with at least one clamping member additionally arranged for movement into and out of clamping alignment with the other clamping member. The ability to take a clamping member out of clamping alignment with the other clamping member allows for sequential engagement of the cleaner with the clamping members, which makes docking more convenient. The movement of the clamping member into and out of clamping alignment may be a pivoting movement. In particular, in use with the docking station mounted on a wall, said pivotable clamping member may be arranged such that, when the docking station is in use mounted on a wall, the clamping member is arranged for pivoting movement away from the wall. This latter arrangement is considered particularly advantageous in reducing the footprint of the docking station on the wall, because the pivotable clamping member moves within the footprint of the docking station.

In a particularly stable arrangement for locking the cleaner in the upright position, the upper clamping member is in the form of a docking cradle arranged to receive a first part of the handheld unit in a sliding fit, the docking cradle being slidable relative to the lower clamping member and resiliently biased towards the lower clamping member, the docking cradle additionally being pivotable away from the wall, in use, for movement out of clamping alignment with the lower clamping member in order to receive said first part of the handheld unit. In this case, the lower clamping member may be a fixed clamping member comprising a locking element for engagement with a second part of the handheld unit to secure the stick-vac against lateral movement relative to the lower clamping member.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a stick-vac cleaner1comprising a hand held suction unit, in the form of a handheld vacuum cleaner3, an elongate wand5and a floor tool7.

Referring toFIG. 2, the handheld vacuum cleaner3comprises a motor-driven fan which is arranged inside a motor casing9for drawing air in through a suction nozzle11positioned at the front of the hand held vacuum cleaner3. Dirty air drawn in through the suction nozzle11is ducted under the fan-generated suction pressure through a cyclonic separation system13, where dirt is separated from the air, before the relatively clean air is then exhausted back to atmosphere via one or more fine-particulate filters (not visible). The dirt which is separated from the airflow inside the cyclonic separating system13is collected in a bin15for disposal. The hand held vacuum cleaner3is powered by a multi-cell rechargeable battery which is housed in a battery pack17.

In use, the handheld vacuum cleaner3is carried in the hand using a handle19.

The handheld cleaner3is relatively compact. Nevertheless, to promote a balanced feel in the hand, the heavier components such as the motor and the battery pack17are deliberately located relatively close to the handle19and the relatively light components such as the bin15are located further away from the handle19. Thus, the bulk of the mass of the handheld cleaner3is distributed towards the rear of the handheld cleaner3.

The elongate wand5is connected to the suction nozzle11, and the floor tool7is in turn connected to the lower end of the wand5. Dirty air is drawn in through a suction opening on the underside of the floor tool5and passes to the suction nozzle11via the wand5.

A catch21is provided for disconnecting the wand5from the handheld cleaner3, so that the handheld cleaner3can be used as a handheld cleaner rather than as part of the stick-vac cleaner1. A catch22is also provided for disconnecting the floor tool7from the wand5, so that rather than being used as part of the stick-vac cleaner1, the handheld cleaner3and wand5can alternatively be used in combination with some other suction tool to form a “long-reach” handheld vacuum cleaner for cleaning into the upper corners of a room etc.

The stick-vac cleaner1is “top-heavy”, and conventionally this type of stick-vac cleaner has been awkward to store when it is not in use. If the stick-vac cleaner1is propped up against a wall in the upright position, with the floor tool7supported on the floor and the handheld cleaner3resting against the wall, the stick-vac cleaner1as a whole tends to be relatively unstable; on the other hand, if the stick-vac cleaner1is propped up against a wall upside down, with the handheld cleaner3supported on the floor and the floor tool7resting against the wall, the inclination is for a user to grasp the relatively dirty floor tool7in order to manipulate the stick-vac cleaner1back to the upright position for use. The relatively dirty floor tool7may also mark the wall.

FIG. 3illustrates an arrangement for conveniently storing the stick-vac cleaner1when it is not in use, in which the stick-vac cleaner1is supported in an upright position on a wall21by a wall-mounted docking station23.

The docking station23is shown in more detail inFIGS. 4 to 6, which illustrate the stick-vac cleaner immediately prior to docking, during docking and in the docked position, respectively.

The stick-vac cleaner1docks with the docking station23via the battery pack17, which slots upwardly (in the direction A inFIG. 4) into a docking cradle25shaped to receive the battery pack17in a close sliding fit. The front wall25aof the docking cradle25incorporates a blind slot27extending back from the entrance of the cradle25: this blind slot27accommodates the handle19as the battery pack is inserted upwardly into the docking cradle25.

A set of charging contacts is provided on the docking station23in the form of a charging jack29, which clips into a jack holder31positioned adjacent the end of the slot27. The charging jack29connects to a mains supply via a plug-in power cord34and is arranged for engagement with a corresponding set of charging contacts on the handheld cleaner3in the docked position, via a charging socket33on the back of the handle19. Engagement of the charging jack29with the charging socket33completes a battery charging circuit for charging the stick-vac cleaner1in the docked position.

A catch35is provided to lock the stick-vac cleaner1securely in the docked position shown inFIG. 6.

The catch35is pivotally mounted on a catch housing36fitted to the side of the docking cradle25and is spring-biased towards a locking position shown inFIG. 4. During docking of the stick-vac cleaner1, the catch35cooperates with a corresponding catch portion37on the handheld cleaner3, which engages with a first cam surface35aon the underside of the catch35to pivot the catch35away from the locking position shown inFIG. 4and into the position shown inFIG. 5. As the handheld cleaner3is moved from the position shown inFIG. 5to the docked position shown inFIG. 6, the catch portion37eventually clears the catch35, which is then spring-biased back towards the locking position, and into locking engagement against the underside of the catch portion37to hold the stick-vac cleaner1in the docked position.

When it is docked with the docking station23, the stick-vac cleaner1is laterally supported in the upright position by the side walls of the docking cradle25. In addition, the side walls of the docking cradle25advantageously provide direct lateral support for the relatively heavy handheld cleaner3.

The weight of the stick-vac cleaner1is effectively supported on the catch35. Again, the catch35advantageously directly supports the relatively heavy handheld cleaner3.

The manufacturing tolerances are controlled so that the catch35holds the charging socket33in engagement with the jack29in the docked position. Thus the battery onboard the handheld cleaner is reliably charged when the stick-vac cleaner1is in the upright, docked position.

Control of manufacturing tolerances may be particularly important in an arrangement such as the one shown inFIGS. 1 to 6, because the charging socket33faces upwards when the stick-vac cleaner is in the upright, docked position so the weight of the stick-vac cleaner tends to pull the socket33away from the jack29.

The potentially negative effects of manufacturing tolerance on charging reliability can be mitigated by spring loading the charging contacts on the docking station. For example, in an alternative embodiment (not shown), the jack holder31may be spring-biased downwardly for ensuring positive engagement of the charging jack29with the charging socket33.

In order to remove the stick-vac cleaner1from the docked position, a user simply releases the catch35using a manual release lever38and slides the stick-vac cleaner downwardly until the battery pack17disengages from the docking cradle25. The stick-vac cleaner is then advantageously in the upright position ready for use.

In order to reduce the tendency for the catch35to jam in the locked position under the weight of the stick-vac cleaner1, which might hinder manual release of the catch35, the top side35bof the catch35is ramped appropriately (seeFIG. 4). Alternatively, the top side of the catch35may be flat (indicated very schematically by the dotted line B inFIG. 6), which has the advantage that the top side cannot then transmit any accidental lateral release force to the catch35, for example as a result of the handheld cleaner3being knocked by a user in the docked position. If the weight of the stick-vac cleaner1tends to jam the catch35, it may be possible nevertheless to use a flat profile catch, but provide a small amount of play to allow a user to lift the stick-vac cleaner1off the catch35prior to manual release of the catch; however, care may need to be taken to ensure that there is not sufficient play to allow the socket33to pull away from the jack29when the stick-vac cleaner is in the upright, docked position shown inFIG. 6.

This docking station23can be secured to the wall21using wall-fixing screws (not shown) which are screwed into the wall21through countersunk clearance holes (not visible) in the rear wall25aof the cradle25. Any other suitably strong conventional wall-fixings may be used to mount the docking station23on the wall21, including surface fasteners such as adhesive pads or the like.

In this case, the stick-vac cleaner1is stored in a fully upright, docked position, with the wand5effectively “hanging” vertically downwards. However, this is not considered necessary to obtain the advantages of the invention, provided that the stick-vac cleaner is stored in an upright position.

FIG. 7shows the docking station23mounted on the wall21in an alternative orientation, using a mounting bracket39which is secured to the wall21(e.g. using screws) and which is arranged to engage with a mounting lug41(FIG. 4) on the docking cradle25to support the docking station23on the wall.

The catch housing36incorporates mounting points for a crevice tool and an upholstery brush, which are retained on the catch housing in a friction-fit.

FIG. 8shows an alternative wall-mountable docking station230for locking the stick-vac cleaner1in an upright, docked position on a wall.

In this arrangement, the handheld unit3is clamped securely in the upright, docked position between an upper clamping member, in the form of a docking cradle250, and a lower clamping member, in the form of a bin support350. The clamping load is represented inFIG. 8by F1and F2, and is in direct opposition to the weight of the cleaner.

The bin support350is fixed to a wall mounting plate370(FIG. 9) which in use is secured flat against the wall, in the orientation shown, using suitable wall fixings. In this particular case, the lower bin support350is actually formed integrally with the wall mounting plate370, though this is not essential. A locking element360(FIG. 9) is provided on the bin support350, which engages with a catch recess15a(just visible inFIG. 11) on the front of the bin15to secure the bin15against lateral movement in the docked position. ‘Universal fit’ tool holders340are provided on the underside of the lower bin support350for retaining tools, or possibly the wand5.

The docking cradle250is similar to the docking cradle25, albeit shorter in length, with the docking cradle250likewise being arranged to receive the battery pack17in a close sliding fit. A blind slot270is provided in the front wall of the docking cradle250to accommodate the handle19, and a mains-operated charging jack290is held within a jack holder310, adjacent the blind end of the slot270, for engaging the charging socket33on the back of the handle19(FIG. 8).

The docking cradle250is supported by a separate carriage plate390(FIG. 9) which can move up and down relative to the wall mounting plate370to vary the (vertical) separation between the docking cradle250and the bin support350. A biasing spring410(just visible inFIG. 9through a window in the carriage plate390) acts between the carriage plate and the mounting plate370to bias the docking cradle250downwardly towards the bin support350. The spring410thus provides a positive clamping action between the docking cradle250and the bin support350which helps to maintain a reliable electrical contact between the charging jack290and the charging socket33in the docked position.

The docking cradle250is pivotally mounted on the carriage plate390via a supporting yoke430. This allows the docking cradle250to be pivoted away from the carriage plate390, about the axis O, to move the docking cradle250out of clamping alignment with the bin support350(seeFIG. 10).

To release the stick-vac cleaner1from the docked position shown inFIG. 8, the user grasps the stick-vac cleaner and pushes the stick-vac cleaner1upwards, moving the docking cradle250against the bias of the spring410until the locking element360clears the catch recess15ain the bin15. Once the locking element360has cleared the catch recess15ain the bin15, the stick-vac cleaner1can then be manipulated to pivot the docking cradle250laterally away from the mounting plate and out of clamping alignment with the bin support350, which then allows the battery pack17to slide out of the docking cradle250, past the front edge of the bin support350, to release the cleaner1(FIG. 11).

Release of the stick-vac cleaner1from the docked position shown inFIG. 8is a one-handed operation, in the sense that a user does not need to use one hand to hold the cleaner1and the other hand to operate the docking station230(the user may of course optionally grasp the cleaner1with two hands when docking or releasing the cleaner1, and indeed the docking station230advantageously allows him or her to do so).

Docking of the cleaner1with the docking station230is also a one-handed operation. To dock the cleaner1with the docking station230following release of the cleaner1, the battery pack17is simply slid back into the docking cradle250and the docking cradle250is then moved, using the cleaner1, back into clamping alignment with the lower bin support350(FIGS. 12 and 13). In this position—once the user lets go of the cleaner1—the cleaner1is automatically clamped between the docking cradle250and the bin support350under the action of the compression spring410, with the locking element360engaging the catch recess15ain the bin15.

The plug-in power cord340extends down behind the mounting plate370, through a channel370awhich is molded into the mounting plate370. The upper end of the channel370ais trumpet-shaped: this helps reduce stress on the cord340during pivoting movement of the docking cradle250. A stop340ais provided on the power cord340to prevent take up of the power cord340inside the channel370aas the docking cradle250is pivoted about the axis O; the use of the stop340afurther reduces stress on the power cord340by ensuring that the length of power cord340remains fixed between the upper end of the channel370aand the jack holder290.

The locking element360is provided with a ramped front surface360a(FIG. 10) to allow the bin15initially to bump over the locking element360as the docking cradle250is moved back into clamping alignment with the bin support350. This simplifies the docking operation, but it is not essential. The locking element may alternatively have a flat front face, or indeed be a fixed locking element, which would then require the user to push the cleaner1and docking cradle250upwards to make sure that the bin15fully clears the locking element before the docking cradle250is moved back into clamping alignment with the bin support350.

The docking station230incorporates a number of features which help reduce accidental damage to the cleaner1and/or docking station230if the cleaner1is subject to a lateral mechanical shock in the upright, docked position. These include the provision of ramped side surfaces (only side surface360bis visible inFIG. 10) on the locking element360which allow the bin15to bump laterally over the locking element360under a lateral impact force, and also the provision of a degree of lateral ‘play’ between the docking cradle250and the carriage390. A guide surface (for example the curved surface350aof the bin support350) may also be provided to guide the cleaner1upwards under a lateral force—so that the lateral load is taken up by movement of the docking cradle250vertically against the bias of the spring410. Guide surfaces may also optionally be provided which guide the cleaner1under a lateral force so that the docking cradle250consequently rotates outwards about the axis “O”, in which case the cleaner1may “break out” and release automatically under a sufficient lateral load.

FIG. 12shows insertion of the battery pack17into the docking cradle250with the docking cradle250having already been moved out of clamping alignment with the bin support350. In practice, following release of the cleaner1from the docked position the docking cradle250will tend to move under its own weight back into clamping alignment with the bin support350. In this case, partially inserting the battery pack17into the docking cradle250, as shown inFIG. 14, will nevertheless tend to pivot the docking cradle250away from the wall and into alignment with the battery pack17, so that one-handed docking of the cleaner1is still possible. This “self-alignment” of the docking cradle250is helped in part by the relatively short length of the docking cradle250(cf. docking cradle25inFIGS. 4 to 6) which allows the battery pack17to be inserted into the docking cradle25at a relatively shallow angle. A biasing spring (not shown) could be used deliberately to bias the docking cradle250back into clamping alignment with the bin support350following release of the cleaner1, if desired.

According to the present invention, either or both of the clamping members on the docking station may be mounted for movement relative to the wall against the action of a resilient bias. For example, in the docking station230the docking cradle250could be fixed to the wall, and the bin support350could be mounted for sliding movement, relative to the docking cradle250, against the action of a biasing spring. If the upper clamping member is fixed, the lower clamping member may be moveable into and out of clamping alignment with the upper clamping member, analogous to the operation of the docking cradle250inFIGS. 11 to 14. In the case of the docking station23, the catch35and/or docking cradle25may also be arranged as clamping members. For example, the catch35may be spring biased so that, in the locking position, the catch actually positively clamps the cleaner1upwardly against the docking cradle25, with the release lever38being used to pivot the catch35out of clamping alignment with the docking cradle25, as desired. The docking cradle25may likewise be spring biased to clamp the cleaner securely against the catch35.

The movement of one of the clamping members (e.g. the docking cradle250) into and out of clamping alignment with the other clamping member (e.g. the bin support350) need not be a pivoting movement. For example, the docking cradle250could be arranged to slide laterally out of clamping alignment with the bin support350. The use of a pivoting clamping member does, however, help minimize the foot print of the docking station.

The use of a first clamping member which can be moved into and out of clamping alignment with an opposing clamping member is advantageous, but not essential for one-handed docking and release. For example, the docking cradle250could alternatively be fixed to the sliding carriage plate390so that it is maintained at all times in clamping alignment with the fixed bin support350. A fixed docking cradle would inhibit insertion of the battery pack to a degree; this could be mitigated to a certain extent, if desired, by minimizing the length of the docking cradle so that the battery pack17can be inserted into the fixed docking cradle at a very shallow angle.