GB2399606A

GB2399606A - Motor vehicle transmission selector mechanisms

Info

Publication number: GB2399606A
Application number: GB0318277A
Authority: GB
Inventors: Ian Gavin Hartley
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2002-09-04
Filing date: 2003-08-05
Publication date: 2004-09-22
Anticipated expiration: 2023-08-05
Also published as: GB2399606B; GB0220495D0; GB0318277D0

Abstract

A selector mechanism 20 is disclosed having a selector lever 33 that is both rotatable and slideable with respect to a support arm 34. Rotation of the lever 33 is used to select one or more ratios from a power-shiftable transmission 12 and sliding motion of the selector lever 33 is used to select one of two ratios from a range change gearbox 13. The selector lever 33 has a hand grip 35 that is positioned in close proximity to the rim 32 of a steering wheel 30 so as to make the selector lever 33 convenient to use.

Description

Motor vehicle transmission selector mechanisms This invention relates to

motor vehicles and in particular to a selector mechanism for a motor vehicle.

It is well known to provide a motor vehicle with a lever mounted on the floor of the motor vehicle to select one or more gear ratios provided by a power-shiftable transmission.

A power-shiftable transmission is one in which the ratios are changed not by physical movement of components by the driver but by power operated means. There are several types of transmission that can be referred to as power-shift transmissions these are continuously variable transmissions having an electronic control means to provide a number of discreet transmission ratios, electronically controlled automatic transmissions and transmissions in which gear ratio selection is performed by electronically controlled actuators.

It is a problem with a floor mounted lever that the lever can become obstructive particularly if a bench type front seat is used in the motor vehicle. Several solutions have been proposed to overcome this problem, for example in US Patent number 5,954,616 the selector lever is mounted on the steering column of the motor vehicle and in US Patent number 5,520, 066 switch means are provided on a steering wheel of the motor vehicle for selecting one or more gear ratios.

Both of these solutions overcome the problem of poor utilisation of floor space and in addition have the advantage that the means used to select the gear ratios is positioned close to one of the hands of the driver so that they are very convenient for use.

It is an object of the invention to provide a selector lever for a motor vehicle having increased versatility and good ergonomics. - 2 -

According to a first aspect of the invention there is provided a selector mechanism for a motor vehicle having a power-shiftable transmission having two or more forward gear ratios to transmit power from an engine to one or more driven road wheels and a steering wheel having a rim portion for use by a driver of the motor vehicle for steering the vehicle and being rotatably mounted by means of a steering column fastened to part of a body structure of the motor vehicle, the selector mechanism providing signals indicating a selection made by the driver to a electronic control unit which controls the transmission, wherein the selector mechanism comprises a selector lever mounted on a support arm having a longitudinal axis and having a hand grip which is in use arranged in close proximity to the rim of the steering wheel, the selector lever being both rotatable and slideable with respect to the support arm in such a way that, on the one hand, rotation of the selector lever about the axis of the support arm in one direction moves the hand grip towards the driver and rotation in the opposite direction moves the hand grip away from the driver to select said two or more gear ratios and, on the other hand, sliding motion of the selector allows the driver to select one of at least two modes of control of the transmission.

Preferably, the support arm is attached at one end to a fixed part of the steering column and the lever is rotatably supported at an opposite end of the support arm.

This has the advantage that if the steering column is moved to adjust the height of the steering wheel the support arm moves with it and so the correct spacing of the hand grip to the steering wheel is maintained. The support arm may be an elongate tubular member.

The power-shiftable transmission may further include a range change gearbox having at least two ratios, corresponding to two modes of control of the transmission and in that case the selector lever may be slideable along the support arm to change between one of said at least two ratios and another of said at least two ratios. - 3

The range change gearbox may have two ratios, there being a high ratio for normal road use and a low ratio for off-road use and the selector lever may be slideable along the support arm in one direction to change from the low ratio to the high ratio and may be slideable in an opposite direction to change from the high ratio to the low ratio.

The hand grip may include an input means used to switch on and off a brake control system used for controlling the descent of the motor vehicle down an incline. The input means may be selected from one of a push-button switch, a slide switch and a rocker switch.

The power-shiftable transmission may be an automatic transmission and the selector lever may be rotatable to select at least a park setting in which the transmission is locked, a neutral setting in which no drive is provided, and a drive setting in which drive is transmitted from the engine of the motor vehicle to one or more road wheels of the motor vehicle. In such a case, the power-shiftable transmission may be controlled to automatically select one of at least three different gear ratios depending upon the operating conditions of the motor vehicle when the selector lever is in the drive setting position and the hand grip may be provided with an input means to hold the power-shiftable transmission in the currently selected gear ratio. The input means may be a pushbutton switch.

The selector lever may be slideable along the support arm in one direction to change from one mode giving automatic control of the transmission to another mode giving semi automatic control of the transmission and may be slideable in the opposite direction to change from the semi-automatic to the automatic mode.

Conveniently, in the semi-automatic mode of, control the rotation of the lever in one direction causes the transmission to change up one gear ratio and rotation in the opposite direction causes the transmission to change down one gear ratio. - 4

The hand grip may be further provided with an input means to engage and disengage an electronically controlled parking brake. The input means may be a push-button switch.

According to a second aspect of the invention there is provided a motor vehicle having a selector mechanism in accordance with the first aspect of the invention.

The motor vehicle may have four road wheels all of which are arranged to be driven by the power-shiftable transmission from the engine.

The invention will now be described by way of example with reference to the accompanying drawing of which: FIG.1 is an outline view of a motor vehicle according to one aspect of the invention; FIG.2 is a front view of a selector mechanism according to another aspect of the invention; FIG. 3 is a side view of the selector mechanism shown in FIG.2; FIG.4 is a cutaway front view of part of a sensor forming part of the selector mechanism shown in FIGS.2 and 3; and FIG.5 is a cross-section along the line v-v on FIG.4.

As shown in FIG. 1, a motor vehicle 10 includes an engine 11 and a powershift transmission having a power-shift five speed gearbox or transmission 12 and a range change gearbox 13 for providing driving torque from the engine 11 via front and rear propeller shafts 8, g and front and rear axles 6, 7 to each of four vehicle driven road wheels 5. Each of the road wheels 5 is provided with a co-rotating brake disc which is acted upon by a brake caliper 16. Although the invention is described with respect to a five speed electronically controlled automatic transmission it is not limited to such a transmission and any power-shiftable transmission that is electronically controllable could be used.

The brake calipers 16 are hydraulically operated by a brake pedal (not shown) and a hydraulic line leads from the brake pedal to a hydraulic brake system 15 and from each brake caliper to the hydraulic brake control system 15. The hydraulic brake system 15 includes a hydraulic pump and valves so that it can increase and decrease the braking pressure independently of the position of the brake pedal and is controlled by an electronic control unit 14.

Each wheel 5 also carries a co-rotating toothed wheel (not shown) and an inductive sensor (not shown) is provided adjacent each toothed wheel and provides a signal to the electronic control unit 14 in the form of a regular wave form voltage, the frequency of which is indicative of the wheel speed.

A selector mechanism 20 is provided to enable the driver to select which gear ratio the five speed transmission 12 is to operate in. The selector mechanism 20 includes a sensor means 21 (not shown on Fig.1) to send a signal to the electronic control unit 14 indicating which gear ratio or gear setting is required to be selected.

An accelerator pedal (not shown) has a continuously variable sensor in the form of a potentiometer associated with it which provides an analogue signal to the electronic control unit 14 which is dependent upon the position, or angle, of the accelerator pedal.

A manually operable switch in the form of a push-button switch 37 (not shown on Fig.1) is also connected to the electronic control unit 14 to switch on and off a brake control system formed by the electronic control unit 14 and the hydraulic brake control system 15.

The brake control system 15 is used to automatically control the speed of descent of the motor vehicle 10 down an incline. - 6 -

In use, the vehicle is driven normally when the switch 37 is switched off. Under these conditions the electronic control unit 14 will operate an anti-lock braking function to prevent locking of the wheels 5. Therefore, if the driver brakes using the brake pedal and insufficient grip is available to provide the desired braking the pressure to the respective locked wheel 5 is reduced in a pulsed manner. This function is carried out in known manner by monitoring the speed and acceleration of each wheel and a detected vehicle speed calculated from the speeds of all the wheels. The detected vehicle speed is calculated by using an average of all the wheel speeds, but ignoring the speeds of any wheels which are detected as locked or spinning. Locked wheels will be released by releasing braking pressure using the anti-lock valves in the hydraulic control unit 15 and spinning wheels will be slowed by applying a braking pressure from the pump within the hydraulic control unit 15.

When the push-button switch 37 is switched on by the driver, to select a hill descent mode, the electronic control unit 14 takes active control of the vehicle's speed, controlling the application and release of the brakes to limit the vehicle's speed.

It will be appreciated that any convenient form of switch can be used to switch on and off the brake control system such as, for example, a rocker switch or a sliding switch and the invention is not limited to the use of a push-button switch.

The operation of such hill descent control systems are described in greater detail in GB Published applications 2,342,969 and 2,341,430 and will not be described further herein.

The rear propeller shaft 8 has a brake disc fastened thereto and a brake caliper 17 is positioned adjacent the brake disc for cooperation therewith. The brake caliper 17 is connected by a pipe to the hydraulic brake control system 15 and is controlled by the electronic control unit 14. A switch means in the form of a push button switch 38 (not shown on FIG.1) is connected to the electronic control unit 14 to apply and release the brake formed by the caliper 17 and the brake disc attached to the rear propeller shaft 8.

The brake formed by the caliper 17 and the brake disc attached to the rear propeller shaft 8 in this way forms an electronically controlled parking brake for the motor vehicle 10.

5With particular reference to Figures 2 to 5 there is shown in greater detail the selector mechanism 20 used in the motor vehicle 10.

The motor vehicle 10 has in addition to the power-shiftable five speed transmission 12 and range change gearbox 13 used to transmit power from the engine 11 to the driven road wheels 5, a steering wheel 30 rotatably mounted by means of a steering column 31 10fastened to part of a body structure of the motor vehicle 10. The steering wheel 30 has a rim portion 32 for use by a driver of the motor vehicle 10 for steering the motor vehicle 10.

The selector mechanism 20 comprises of a selector lever 33 mounted on a support arm 34 having a longitudinal axis and a hand grip 35 is attached to an upper end of the selector lever 33 for use by the driver of the motor vehicle to select two or more gear ratios.

15The support arm 34 is in the form of an elongate conductive tubular member which permits the passage of electrical cables or wires therethrough and is connected to electrical earth by means of a connection to the steering column 31.

The hand grip 35 is positioned in close proximity to the rim 32 of the steering wheel 30. The selector lever 33 is both rotatable and slideable with respect to the support arm 34 20in such a way that, on the one hand, rotation of the selector lever 33 about the axis of the support arm 34 in one direction ('a' on FIG.3) moves the hand grip 35 towards the driver and rotation in the opposite direction ('b' on FIG.3) moves the hand grip 35 away from the driver to select said two or more gear ratios and, on the other hand, sliding motion of the selector 33 allowing the driver to select one of at least two modes of control of the transmission. - 8 -

As shown the selector lever 33 is rotatably mounted on the support arm 34 by means of a selector housing 39 and is rotatable relative to the support arm 34 to select said one or more gear ratios. The support arm 34 is attached at one end to a fixed part of the steering column 31 of the motor vehicle 10 and the selector lever 33 is rotatably supported at an opposite end of the support arm 34 by means of the selector housing 39. However, it will be appreciated that the selector lever could be fixed to the support arm and the support arm could be moveably attached to the steering column.

The range change gearbox 13 has two ratios, there being a high ratio for normal road use and a low ratio for off-road use, corresponding to two modes of control of the transmission. The selector lever 33 or to be more precise the selector housing 39 is slideable along the support arm 34 in one direction to change from the low ratio to the high ratio and is slideable in an opposite direction to change from the high ratio to the low ratio.

It will be appreciated that the range change gearbox could include more than two ratios if required.

As can best be seen with reference to FIGS. 4 and 5 the selector housing 39 is slideably engaged with the support arm 34 and houses the sensor means 21 used to select a desired gear ratio within the five speed transmission 12 and also to select one of four modes of control transmission, i.e. one mode giving automatic control of the transmission, another mode giving semi-automatic mode of the transmission and for each said modes a high or low range in the range change gearbox 13.

As shown the sensor means 21 is in an electrical form but it will be appreciated that an optical arrangement could be used and that the invention is not limited to the use of the sensor means shown and described herein.

The sensor means 21 comprises of a non-conductive sleeve 42 fastened to the support arm 34, a first group of separate conductive pads P. R. N. D, 4, 3 and L, corresponding to automatic control of the transmission, each of which is attached to the sleeve 42 and is connected via a respective electrical connection 49 routed through the hollow support arm 34 to the electronic control unit 14, a second group of conductive pads +' and '-', corresponding to semi-automatic control of the transmission, each of which is attached to the sleeve 42 and is connected to the electronic control unit 14 by a respective electrical connection (not shown) routed through the support arm 34 and two parallel conductive tracks 40, 41 each of which is connected to the electronic control unit 14 by means of a respective electrical connection 46, 47.

The conductive pads P. R. N. D, 4, 3 and L represent various gear ratio settings within the five speed transmission 12. The pad 'P' corresponding to a transmission park setting in which the transmission is locked, the pad 'N' corresponding to a neutral setting in which no drive is provided, the pad 'D' corresponding to a drive setting in which drive is transmitted from the engine of the motor vehicle to one or more road wheels of the motor vehicle, the pad '4' corresponding to a setting in which all driveable gears up to and including fourth gear may be selected, the pad '3' corresponding to a setting in which all driveable gears up to and including third gear may be selected and the pad 'L' corresponding to a setting in which only first or second gear may be selected.

The selector housing 39 is made from a conductive material and is both slidingly and rotatably engaged with the support arm 34 by means of slipper portions 48 formed at each end. The selector housing 39 is engaged over the non-conductive sleeve 42 and supports two spring loaded contacts 44, 45. The sprung contact 44 is provided for cooperation with the conductive pads P. R. N. D, 4, 3 and L or '+', '-' and the sprung contact 45 is provided for cooperation with the conductive tracks 40, 41.

The selector lever 33 is threadingly engaged with the selector housing 34 so that the selector housing 39 is moveable by the hand grip 35 and is either coated with a non- conductive material or is made from a non conductive material. - 10

Operation of the sensor means 21 is as follows.

With the selector housing 39 positioned in its most leftward position the sprung loaded contacts 44, 45 are aligned as shown by the joined arrows 50 on FIG.4. It will be appreciated that the left arrow represents the sprung contact 44, the right arrow represents the sprung contact 45 and the line joining the two arrows represents the selector housing 39.

In the position shown, an electrical circuit is made between the electrical pad 'L' and the sprung loaded contact 44 which is connected to earth via the selector housing 39 but no contact is made between the sprung contact 45 and either of the two parallel conductive tracks 40, 41 because the sprung contact 45 is resting on the non-conductive surface of the sleeve 42.

The electronic control unit 14 therefore receives a signal along the electrical connection 49 indicating that the setting equating to the 'L' position is required. In effect the electrical control unit 14 will receive a signal equivalent to '0' or '1' depending upon whether a connection to earth has been made via the respective pad P. R. N. D, 4, 3, L. The receipt by the electronic control unit of a '1' signal from the 'L' pad indicates that the desired setting for the five speed transmission 12 is one in which only first and second gears can be used. The electronic control unit 14 then sends a signal to an actuator 18 fitted to the five speed transmission 12 to select the desired gear ratios.

A similar arrangement is employed for the range change gearbox 13. When a circuit is made via the conductive track 40 and the sprung loaded contact 45 the control unit 14 interprets this signal as a '1' signal and when no circuit is made the electronic control unit 14 interprets this as a '0' signal. The electronic control unit 14 is programmed to select low range in the range change gearbox 13 when a '1' is received and select high range in the range change gearbox 13 when a '0' is received. In the event of a poor contact in which an intermittent signal is received the electronic control unit 14 will default to high range to prevent hunting between high and low.

Therefore with the selector housing positioned such that no contact is made between the sprung contact 45 and the conductive track 40 the electronic control unit 14 sends a signal to an actuator 19 on the range change gearbox 13 to select high range.

If the selector housing 39 is then slid to the right the sprung contact 45 will make contact with the conductive track 40 (as indicated by the joined arrows 51 on FIG.4). This causes a '1' signal to be sent to the electronic control unit 14 indicating that low range is required from the range change gearbox 13. This is because the engagement of the sprung contact 45 with the conductive track 40 completes an electrical circuit to earth via the selector housing 39 and the electronic control unit 14 senses this via the electrical connection 46.

It will however be appreciated that the selection of high and low ranges could be achieved in some other manner. For example a switch could be provided on the hand grip or the selector lever could pivot relative to the selector housing however the sliding motion of the selector housing relative to the support arm is the preferred method of selection.

It will be appreciated that if the selector housing 39 is then rotated clockwise from the position shown (that is to say in the direction of arrow 'b' on FIG.3) the sprung loaded contact 44 will sequentially make contact with each of the other conductive pads 3,4, D, N. R and P. In each case when contact is made the electronic control unit 14 will send a corresponding signal to the actuator 18 to select the requested gear ratios.

The electronic control unit 14 continuously monitors all of the inputs from the conductive pads P. R. N. D, 4, 3 and L to determine which of the available gear settings is required. If no signal is received from any of the pads P. R. N. D, 4, 3 and L then the electronic control unit 14 is arranged to maintain the current gear setting until a signal is - 12 received from one of the pads P, R, N, D, 4, 3 and L. This is to ensure that when the sprung contact 44 moves from one pad to another pad the system is stable and the electrical control unit 14 will not try to select more than one of the various gear settings simultaneously.

When in the drive setting position corresponding to selector housing 39 position in which the sprung contact 44 is in contact with the conductive pad 'D' the power-shiftable transmission automatically selects any one of the five different forward gear ratios depending upon the operating conditions of the motor vehicle. To enable the five speed transmission 12 to be temporarily held in the currently selected ratio, the hand grip 35 is provided with an input means in the form of a push-button switch 28. While the button is held depressed automatic control of the five speed transmission is suspended and the current gear ratio is held, as soon as the push-button switch 28 is released normal automatic control of the five speed transmission 12 is resumed.

It will be appreciated that other forms of switch could be used instead of a push-button switch these could be of a type arranged so that a gear ratio is held only as long as pressure is applied by the driver to the switch or may be of a type that provide a lock out function in which continuous pressure is not required but the switch when operated provides a single pulse which is interpreted by the electronic control unit as a request to hold a particular gear until a pre-determined maximum engine speed is attained.

In a similar manner to that described with respect to control of the five speed transmission 12, the electronic control unit 14 continuously monitors the inputs from the conductive tracks 40, 41 to determine which of the available gear settings within the range change gearbox 13 is required. If no signal is received then the electronic control unit 14 automatically defaults to the selection of the high range. - 1 3

It will be appreciated that the electronic control unit 14 includes further programming to ensure that a dangerous combination of ratios is not selected such as for example selecting low range when the motor vehicle is travailing at high speed or maintaining a specific ratio above the maximum safe working speed of the engine 11. However, all of the available gear ratios of the five speed transmission 12 can be selected in both high and low ranges.

The conductive pads '+' and '-' are used to effect semi-automatic control of the five speed transmission. The selector housing 39 is moved further to the right than the position for the selection of the low range (as indicated by the joined arrows 60). In this position, the sprung contact 44 can make contact with either the '+' contact, the '-' contact or makes no contact at all and sits on an insulated land 62 between the contacts '+ ' and '-'.

A spring means (not shown) is used to maintain the sprung contact 44 on the insulated land 62 until the selector housing 39 is rotated by means of a driver input via the selector lever 33. In addition, guide means (not shown) are provided to ensure that the selector housing 39 can only be moved into this position from the drive position and that the sprung contact 44 automatically assumes a position on the insulated land 62.

In this semi-automatic mode of operation the electronic control unit 14 is operational to control the five speed transmission 12 in accordance with the inputs received from the selector lever 33 and automatic control of the five speed transmission 12 is suspended except to the extend that an up-change may be made to prevent engine overspending and down-change may be made to prevent engine stalling.

Rotation of the selector lever 33 away from the driver (e.g. in the direction of arrow 'b' on FIG.3) will cause the sprung contact 44 to engage with the contact '-' thereby sending a 1' signal along the respective electrical connection to the electronic control unit 14. The electronic control unit 14 sends in response a signal to the actuator 18 to select one ratio - 14 lower of the available ratios in the five speed transmission 12. If the lowest ratio is already selected then no further action is taken.

Similarly, rotation of the selector lever 33 towards the driver will cause the sprung contact 44 to engage with the contact '+' thereby sending a'1'signal along the respective electrical connection to the electronic control unit 14. The electronic control unit 14 sends in response a signal to the actuator 18 to select one ratio higher of the available ratios in the five speed transmission 12. If the highest ratio is already selected then no further action is taken.

In this mode of operation it is not possible to select reverse gear, neutral gear or the park setting of the five speed transmission 12. To select any of these settings the selector lever must be slid back to the left to re-engage with one of the conductive pads P. R or N. However, selection of the low range is possible by moving the selector housing 39 still further to the right into the position indicated by the joined arrows 61. In this position the sprung contact 45 contacts the conductive track 41. As before, when contact is made between the sprung contact 45 and the conductive track 41 a '1' signal is sent to the electronic control unit 14 via the electrical connection 47 and the low range is selected in the range change gearbox 13 by the actuator 19.

The hand grip 35 is fitted with an input means in the form of the pushbutton switch 37 used to switch on and off the brake control system 15 used for controlling the descent of the motor vehicle down an incline. It will be appreciated that the input means need not be a push-button switch but could be any type of suitable switch such as slide switch or a rocker switch. In any event operation of the switch will either engage or disengage the brake control system.

The hand grip 35 is further fitted at its upper end with an input means in the form of the push-button switch 38 to engage and disengage the electronically controlled parking - 15 brake. It will be appreciated that the input means need not be a push-button switch but could be any type of suitable switch such as slide switch or a rocker switch. In any event operation of the switch will either engage or disengage the parking brake. - 16

Claims

1. A selector mechanism for a motor vehicle having a power-shiftable transmission having two or more forward gear ratios to transmit power from an engine to one or more driven road wheels and a steering wheel having a rind portion for use by a driver of the motor vehicle for steering the vehicle and being rotatably mounted by means of a steering column fastened to part of a body structure of the motor vehicle, the selector mechanism providing signals indicating a selection made by the driver to a electronic control unit which controls the transmission, wherein the selector mechanism comprises a selector lever mounted on a support arm having a longitudinal axis and having a hand grip which is in use arranged in close proximity to the rim of the steering wheel, the selector lever being both rotatable and slideable with respect to the support arm in such a way that, on the one hand, rotation of the selector lever about the axis of the support arm in one direction moves the hand grip towards the driver and rotation in the opposite direction moves the hand grip away from the driver to select said two or more gear ratios and, on the other hand, sliding motion of the selector allows the driver to select one of at least two modes of control of the transmission.

2. A selector mechanism as claimed in claim 1 in which the support arm is in use attached at one end to a fixed part of the steering column and the lever is rotatably supported at an opposite end of the support arm.

3. A selector mechanism as claimed in any of claims 1 or in claim 2 in which the support arm is an elongate tubular member.

4. A selector mechanism as claimed in any of claims 1 to 3 for use when the power- shiftable transmission further includes a range change gearbox having at least two ratios, corresponding to two modes of control of the transmission and wherein the - 1 7 selector lever is slideable along the support arm to change between one of said at least two ratios and another of said at least two ratios.

5. A selector mechanism as claimed in claim 4 for use when the range change gearbox has two ratios, there being a high ratio for normal road use and a low ratio for off-road use and wherein the selector lever is slideable along the support arm in one direction to change from the low ratio to the high ratio and is slideable in an opposite direction to change from the high ratio to the low ratio.

6. A selector mechanism as claimed in any of claims 1 to 5 in which the hand grip includes an input means used to switch on and off a brake control system used for controlling the descent of the motor vehicle down an incline.

7. A selector mechanism as claimed in claim 6 in which the input means is selected from one of a push-button switch, a slide switch and a rocker switch.

8. A selector mechanism as claimed in any of claims 1 to 7 for use where the power- shiftable transmission is an automatic transmission and wherein the selector lever is rotatable to select at least a park setting in which the transmission is locked, a neutral setting in which no drive is provided, and a drive setting in which drive is transmitted from the engine of the motor vehicle to one or more road wheels of the motor vehicle.

9. A selector mechanism as claimed in claim 8 for use where, the powershiftable transmission is controlled to automatically select one of at least three different gear ratios depending upon the operating conditions of the motor vehicle when the selector level is in the drive setting position and wherein the hand grip is provided with an input means to hold the power-shiftable transmission in the currently selected gear ratio.

10. A selector mechanism as claimed in claim 9 in which the input means is a push-button switch. - 1 8

11. A selector mechanism as claimed in any of claims 1 to 9 in which the selector lever is slideable along the support arm in one direction to change from one mode giving automatic control of the transmission to another mode giving semi-automatic control of the transmission and is slideable in an opposite direction to change from semi- automatic to the automatic mode.

12. A selector mechanism as claimed in claims 11 in which in the semiautomatic mode of control the rotation of the lever in one direction causes the transmission to change up one gear ratio and rotation in the opposite direction causes the transmission to change down one gear ratio.

13. A selector mechanism as claimed in claim 12 in which rotation of the selector lever towards the driver causes the transmission to change up one gear ratio and rotation of the selector lever away from the driver causes the transmission to change down one gear ratio.

14. A selector mechanism as claimed in any of claims 1 to 14 in which the hand grip is further provided with an input means to engage and disengage an electronically controlled parking brake.

15. A selector mechanism as claimed in claim 14 in which the input means is a push- button switch.

16. A motor vehicle having a selector mechanism as claimed in any of claims 1 to 15.

17. A motor vehicle as claimed in claim 16 in which the motor vehicle has four road wheels all of which are arranged to be driven by the powershiftable transmission from the engine. - 1 9

18. A selector mechanism for a motor vehicle having a power-shiftable transmission and a steering wheel, the selector mechanism being substantially as described herein with reference to the accompanying drawing.

19. A motor vehicle substantially as described herein with reference to the accompanying drawings.