GB1592448A

GB1592448A - Change speed gearing

Info

Publication number: GB1592448A
Application number: GB4969076A
Authority: GB
Original assignee: Lamburn A S
Current assignee: Lamburn A S
Priority date: 1977-11-25
Filing date: 1977-11-25
Publication date: 1981-07-08

Description

(54) CHANGE SPEED GEARING (71) I, ALAN SALISBURY LAMBURN, a British Subject, of The Old Rectory, Kencott, Via Lechlade, Gloucestershire, GL7 3QX, do hereby declare the invention for which I pray that a Patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to change-speed gearing and is particularly, but not exclusively, concerned with a method of and apparatus for drivably connecting an auxiliary change-speed gearing to a main changespeed gearing of a motor vehicle.

Although many vehicles leaving manufacturers' production lines have change-speed gearings which include an overdrive ratio, the majority of vehicles, in particular fourwheel drive vehicles, still require the after market sale and fitting of auxiliary overdrive units where an overdrive ratio is required. In four-wheel drive vehicles, the drive output shaft of the main change-speed gearing is usually splined to a spur gear wheel through which drive is transmitted to a transfer gearing for the vehicle. When fitting an auxiliary unit, it is necessary to remove this spur gear so that drive will be transmitted to the transfer gearing via the auxiliary gearing. To keep fitting costs to a minimum, it is essential to ensure that the auxiliary unit can be fitted with a minimum of alteration to the existing gearing. Therefore, the output from the auxiliary gearing should ideally comprise a spur gear of identical size to that which has to be removed, and should be positioned in the same place so as to be capable of transmitting drive to the transfer gearing as before. To achieve this ideal, two major problems have to be overcome. One of these is the difficulty of drivably connecting the drive output shaft of the main change-speed gearing to the drive input of the auxiliary unit in the space which is available. The other problem is that of suitably supporting the output end of the drive output shaft of the main change-speed gearing when the auxiliary unit is fitted. This problem arises in view of the fact that the drive output shaft is normally supported in a casing part of the transfer gearing which has to be removed to enable the auxiliary unit to be fitted. An object of the invention is to mitigate these problems.

According to the invention, a method of drivably connecting an auxiliary changespeed gearing to a main change-speed gearing includes drivably connecting a drive output member of said main change-speed gearing to a drive input member of said auxiliary change-speed gearing, which is arranged coaxially within a tubular drive output member of the auxiliary change-speed gearing, rotatably supporting a tubular drive output member of said auxiliary change-speed gearing in bearing means located between the outer surface of said tubular drive output member and a casing for said auxiliary change-speed gearing, and rotatably supporting said drive output member of the main change-speed gearing by support means including further bearing means which engages the inner surface of said tubular drive output member each side of a plane containing the first said bearing means.

Preferably, the drive output member from the main change-speed gearing comprises a drive output shaft arranged to be drivably connected to the drive input member of the auxiliary change-speed gearing by means of a sleeve extending within the tubular drive output member. In the case where the drive output shaft of the main change-speed gearing normally has its output end supported by a casing part which has to be removed to enable the auxiliary change-speed gearing to be fitted, the method preferably includes supporting said output end by means of a member of said support means which engages the inner surface of the sleeve adjacent the output end of said drive output shaft.

The method may include connecting the member of said support means to the sleeve by splines.

In the case where the drive output from the main change-speed gearing includes a spur gear through which drive is normally transmitted to a transfer gearing, it will be necessary to remove the spur gear when fitting the auxiliary change-speed gearing, and replace it with the aforesaid sleeve. The spur gear is often held in place by means of a nut which screws on to threads formed on the drive output shaft adjacent the output end thereof.

Usually, the nut prevents appreciable axial movement of the drive output shaft towards the main change-speed gearing, and it is desirable to provide means for performing the function of the nut after the spur gear has been replaced by the sleeve. In such a case, the method may include replacing the nut by a screw-threaded retainer which fits within the sleeve, the screw-threaded retainer including, or being arranged to co-operate with, abutment means for abutting the axially inner ends of splines on the sleeve which drivably connect the sleeve to the drive output shaft. Preferably, the screw-threaded retainer is formed with a portion constituting the aforesaid member of the support means which engages the inner surface of the sleeve for the purpose of supporting the output end of the drive output shaft.

Another problem which arises with auxiliary change-speed gearings is that concerned with the lubrication of working parts. It is known to provide such gearings with their own supply of lubricating oil which is completely separate from that of the main change-speed gearing the transfer gearing or other external reservoir. However, this is generally disadvantageous as the oil level in the auxiliary unit nceds to be checked separately from the main change-speed geanng and requires separate filling and topping-up operations. Also, the auxiliary gearing normally contains considerably less lubricant than the main change-speed gearing or transfer gearing. As a result, the lubricant may be subject to rapid temperature rises during operation of the auxiliary gearing. Therefore, in a preferred embodiment the auxiliary change-speed gearing is lubricated by collecting the lubricant from an external reservoir, allowing the collected lubricant to lubricate the auxiliary gearing and subsequently to col lect in a sump, and allowing the lubricant in the sump to reach a level determined by the position of an outlet duct through which the lubricant will return to said reservoir.

Yet another problem which arises, particularly with epicyclic gearings, is the fact that the lubricant tends to centrifuge towards the casing of the auxiliary unit. This gives rise to the necessity of feeding lubricant into the central area of the auxiliary change-speed gearing. Therefore, the auxiliary changespeed gearing, when of the epicyclic-type may be lubricated by collecting lubricant from the external reservoir, and ducting the collected lubricant through a feed passage to a lubricant tube which extends axially of the epicyclic gearing and generally through the centre region thereof so as to duct the lubricant to a distribution outlet from which the lubricant will travel by centrifugal force to lubricate the auxiliary change-speed gearing.

Preferably the lubricant is fed by gravity through the feed passage to the lubricant tube.

The invention also includes apparatus for performing the method according to the invention as set out hereinbefore.

Hitherto, it has been proposed to actuate auxiliary change-speed gearings for fourwheel drive vehicles by means of a mechanical linkage. Although such an arrangement is generally satisfactory, it can lead to additional complications when fitting. Therefore, I propose to actuate the auxiliary changespeed gearing by means of servo having a reciprocable operating rod to be connected to ratio selector means of said auxiliary change-speed gearing, said operating rod being rotatably connected to diaphragm means in said servo to enable the operating rod to rotate relatively to the servo. Such an arrangement enables apertures in adaptor means carried by the servo to be easily aligned with studs on the casing of the auxiliarv gearing after the operating rod has been atfached to the ratio selector means.

In the case where the auxiliary changespeed gearing is of the epicyclic type and includes a sun gear wheel, the sun gear wheel, may be mounted for rotation on a spigot fast with the casing of the auxiliary gearing.

Where the epicyclic gearing includes planet gear wheels mounted for rotation on pins of a planet gear wheel carrier, each pin, may be formed with a recess or rebate at one end engageable with retaining means which may be part of or arranged adjacent said planet gear wheel carrier to prevent rotation or axial displacement of each pin.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-section through one form of auxiliary change-speed gearing drivably connected to a drive output shaft of a main change-speed gearing for a motor vehicle; Figure 2 is a cross-section of the auxiliary change-speed gearing of Figure 1 on the line II-II in Figure 1 Figure 3 is an end view of a planet gearwheel carrier of the change-speed gearing of Figure 1; Figure 4 is a diagrammatic cross-section through part of the casing of the changespeed gearing of Figure 1; Figure 5 is a part cross-section through a further form of auxiliary change-speed gearing connected to a drive output shaft of a main change-speed gearing for a motor vehi cle; and Figure 6 is an elevation of a preferred form of vacuum-operable servo, shown partly broken away, for actuating the auxiliary change-speed gearing.

Referring firstly to Figure 1, an auxiliary change-speed gearing includes an epicyclic gearing indicated generally at 26. The epicyclic gearing 26 is housed in first and second casing portions 27, 28, the casing portion 27 being attachable to a casing 29 of a gearing (not shown) such as a transfer gearing of a four-wheel drive vehicle. The main change-speed has a splined drive output shaft 32 which normally carries a spur gear wheel (not shown) retained axially on the shaft 32 by a nut (also not shown) which threadedly engages a screw-threaded portion 33 of the shaft 32. The spur gear wheel normally carried by the shaft 32 meshes with a further gear wheel (not shown) to transmit drive to the transfer gearing of the four-wheel drive vehicle. When the auxiliary change-speed gearing is fitted, it is necessary to transmit drive from the shaft 32 to a tubular, internally splined input member 34 of the epicyclic gearing. This may be achieved by utilising a sleeve 35 having two axially splined portions 36, 37, the splines 36 being complementary to the splines on the shaft 32 and the splines 37 being complementary to the splines on the drive input member 34.

After removing the spur gear from the shaft 32, the sleeve 35 is located on the drive output shaft 32, and a wsher 39 is positioned against a shoulder 36a adjacent the righthand ends of the splines 36. A screwthreaded retainer 40 is then inserted in the sleeve 35 and is rotated by a suitable tool inserted in a socket 41 in the retainer, whereby the retainer will threadedly engage the threaded portion 33 and urge the washer 39 against a shoulder 36a adjacent the right-hand ends of the splines 36. The retainer 40 has an internal bore 47 which fits closely over an extension 48 of the shaft 32.

The extension 48 is normally supported by a bearing in a casing part of the transfer gearing which has to be removed to enable the auxiliary change-speed gearing to be fitted.

As it is necessary to provide support for the extension 48, the right-hand end of the retainer 40 is formed to define a cylindrical support 49 which fits closely within the sleeve 35. The support 49 maintains the retainer 40, and hence the extension 48 in coaxial relationship with the sleeve 35. When connecting the auxiliary change-speed gearing to the transfer gearing, the auxiliary unit is manoeuvred to interengage the splines 37 and the splines on the input member 34. The external surface of the sleeve 35 is rotatably supported by bearings 42, 43 carried by a tubular drive output member 44 of the epicyclic gearing 26. The drive output member 44 is itself supported for rotation by a journal bearing 45 mounted in the casing portion 27. The bearings 42,43 are arranged one each side of a plane containing the bearing 45. If desired, the two bearings 42, 43 could be in the form of sprayed-bronze bearing surfaces or a single bearing extending each side of the aforesaid plane. The lefthand end of the drive output member 44 is splined to a spur gear wheel 46 of identical dimensions to the spur gear wheel removed from the shaft 32. The spur gear wheel 46 meshes with the aforesaid further spur gear wheel to transmit drive directly or at an overdrive ratio to the transfer drive transmission.

A lubrication system for the auxiliary gearing shown in Figure 1 will now be described.

The casing portion 27 is formed with a lubricant entry 60 which is located immediately beneath a lubricant deflector 62 carried by a plate 63 in the casing 29 of the transfer gearing. Iri use, the lubricant deflector directs splashed lubricant in the transfer gearing into the entry 60. The lubricant deflector defines a trough 62a which extends across the spur gear wheel 46 and which collects lubricant thrown from the spur gear wheel. The lubricant deflector directs lubricant from the transfer gearing into the entry 60 which has two outlets 61, 64 (see Figure 2). When lubricant is fed to the entry 60 faster than it can pass through the outlet 64, the entry fills up and excess lubricant passes through the outlet 61 and on to the drive output member 44. The lubricant is effective for general lubrication and heat transfer purposes and will eventually pass into the bottom of the casing portions 27, 28. The lubricant passing through the bore 64, travels by gravity via a bore 65 and further bores (not shown) in casing portions 27, 28 to a central bore 66 in a spigot 67 of a support member 67a. The support member 67a includes a synchroniser cone 68 and is bolted to the casing portion 28. The bore 66 locates a lubricant tube 69 which extends through the socket 41 in the retainer 40. A certain amount of lubricant in the bore 66 passes through a radial bore 70 formed therein, and through a further radial bore 72 in an extension 73 of a sun gear wheel 74, to lubricate a synchromesh ratio selector means indicated generally at 26a. The sun gear wheel is rotatably mounted on a bearing 67b carried by the spigot 67. The remainder of the lubricant in the bore 66 passes through the tube 69 and into the right-hand portion of the retainer 40.

The retainer 40 has a radial bore 75 through which lubricant passes by virtue of centrifugal force, the lubricant subsequently being centrifuged through a radial bore 76 in the sleeve 35 and into a space between the bearings 42, 43. The bearing 42 has a lubricant groove (not shown) generally of halfelliptical form having its inlets at the righthand end of the bearing. Such a groove provides adequate lubrication of the bearing 42 with minimum loss of lubricant from the left-hand end of the bearing. The bearing 43 is formed with a lubricant feed-scroll 77 which transfers lubricant from the space between the bearings 42, 43 into an annular space 78 between the drive input and drive output members 34, 44. The lubricant then travels towards a thrust washer 78a which has unshown radial slots therein to enable the lubricant to reach a collector plate 81 secured to the periphery of a planet gear wheel carrier 71. The plate 81 has cylindrical extension 81a which engages the edges of flate 79 (see also Figure 3) formed at the left-hand ends of pins 79a (one only of which is shown). The extension 81a prevents rotation of th pins 79a relatively to the carrier 71.

Instead of forming the pins with flats 79a, they could be formed with convex cut-outs or like recesses or rebates facing radially inwardly to engage the periphery of an annular member arranged between the carrier 71 and the drive output member 44. Alternatively, the plate 81 or the said annular member could be replaced by retaining means forming part of the carrier 71. The pins 79a support planet gear-wheels 80 on needle roller bearings 82. Each pin 79a is formed with an axial bore 83 which communicates with a radial bore 84. Lubricant collected by the plate 81 enters the bores 83 and passes through the bores 84 to lubricate the needle roller bearings 82. The lubricant escaping from between the pins 79a and the planet gear-wheels 80 travels outwardly and lubricates the planet gear-wheel teeth and the teeth of an annulus gear 87 meshing therewith. The lubricant finally runs into a sump 20 at the bottom of the casing of the auxiliary change-speed gearing as shown diagrammatically in Figure 4. In order to avoid the nced to provide external pipework to duct lubricant back to the transfer gearing, it is necessary to provide a return duct 88 in the casing of the auxiliary gearing to the left of the annulus gear 87. However, due to he close proximity of the annulus gear 87 to the interior of the casing portion 27, it is likely that the rotating annulus gear 87 will create discs of centrifuged lubricant at its ends. Such discs may prevent lubricant from reaching the return duct 88. Therefore the casing portion 27 is formed with a by-pass duct 89 which will carry lubricant to the left of the annulus gear 87 and hence to the return duct 88. The level of lubricant in the casing is determined by the position of the return duct 88.

An alternative form of driving connection between the drive output shaft of the main change-speed gearing and the drive input of a further type of auxiliary change-speed gearing is shown in Figure 5. In Figure 5 parts correspouding to parts shown in Figure 1 carry like reference numerals. The drive output shaft 32 is splined via an intermediate sleeve 51 to an internally splined sleeve 52.

Splines at the right-hand end of sleeve 52 interengage splines on the drive input member 34 of the auxiliary change-speed gearing and splines on an intermediate member 58 which supports the extension 48.

A clearance 59 is defined between the extension 48 and a bore 55 in the drive input member 34. The clearance 59 allows the drive input member 34 to take up a radial position dictated by the planet gear wheels and annulus gear during operation of the epicycle gearing without being constrained by the extension 48. The sleeves 51, 52 are retained on the shaft 32 by means of a snapring 53 which abuts an intermediate shim 54.

The drive input member 34 is formed with one or more lubricant ducts 56. The sleeve 52 is rotatably supported by needle roller bearings 42, 43 on the drive output member 44. The bearings 42 are spaced from the bearings 43 by a tube 10, and are arranged one each side of the vertical plane containing the bearing 45.

A lubrication system as described with reference to Figures 1 to 4 may be provided for the auxiliary change-speed gearing shown in Figure 5, except that lubricant leaving the tube 69 passes through the or each duct 56 to lubricate the needle roller bearings 43 and the planet gear wheel bearings. The needle roller bearings 42 are lubricated by splashed lubricant in the transfer gearing.

By lubricating the auxiliary change-speed gearing with lubricant from the transfer gearing, the temperature of the lubricant in the casings of the transfer and auxiliary gearings will be substantially equal during operation.

Furthermore, it is unnecessary to effect separate lubricant filling or topping-up operations for respective gearings. This Is clearly advantageous over known auxiliary changespeed gearings which carry their own lubricant completely separate from that of an associated gearing.

The ratio selector mechanism for each of the auxiliary change-speed gearings illustrated preferably includes a vacuum operated servo indicated generally at 90 in Figure 6. The servo is preferably arranged to actuate a reciprocable pushrod 92 to be operatively connected to a supporting shaft 93 (see Figure 1) of a selector fork 94. The servo 90 is arranged to be bolted to the casing of the auxiliary or transfer gearing by means of studs 95 on the casing portion 28 to be located in apertures 98 formed in an adaptor 96 carried by the servo 90. The servo pushrod and the shaft 93 may be interconnected by screwing one into the other. After the shaft 93 has been screwed into the servo pushrod, it will be essential to ensure that the pushrod can be rotated relatively to the servo casing to enable the apertures in the adaptor 96 to be aligned with the studs 95 and to enable the servo 90 to be bolted to the casing portion 28. Conveniently, the servo includes a flexible diaphragm 97 connected to the pushrod by means of central clamping plates 99 arranged one each side of the diaphragm.

The pushrod is rotatably connected to the clamping plates to enable the pushrod to rotate relatively to the servo, the diaphragm 97 sealingly engaging the periphery of the pushrod 92 between the two clamping plates 99.

Instead of using a vacuum or other servo, the ratios may be manually selected through a suitable mechanical linkage.

WHAT I CLAIM IS: 1. A method of drivably connecting an auxiliary change-speed gearing to a main change-speed gearing including drivably connecting a drive output member of said main change-speed gearing to a drive input member of said auxiliary change-speed gearing which is arranged coaxially within a tubular drive output member of the auxiliary change-speed gearing, rotatably supporting the drive output member of said auxiliary change-speed gearing in bearing means located between the outer surface of said tubular drive output member and a casing for said auxiliary change-speed gearing, and rotatably supporting said drive output member of the main change-speed gearing by support means including further bearing means which engages the inner surface of said tubular drive output member each side of a plane containing the first said bearing means.

2. A method, according to Claim 1 and where the drive output member from the main change-speed gearing comprises a drive output shaft, including drivably connecting the drive output shaft to the drive input member of the auxiliary change-speed gearing by means of a sleeve extending within the tubular drive output member.

3. A method, according to Claim 2 and where the drive output shaft of the main change-speed gearing normally has its output end supported by a casing part which has to be removed to enable the auxiliary changespeed gearing to be fitted, including supporting said output end by means of a member of said support means which engages the inner surface of the sleeve adjacent the output end of said drive output shaft.

4. A method, according to Claim 3, including connecting the member of said support means to the sleeve by splines.

5. A method, according to Claim 3 or 4 and where the drive output shaft normally carries a spur gear held in place by a nut, which spur gear and nut have to be removed when drivably connecting the auxiliary change-speed gearing to the main changespeed gearing, including replacing the nut by a screw-threaded retainer which fits within the sleeve, the screw-threaded retainer including, or being arranged to co-operate with, abutment means for abutting the axially inner ends of splines on the sleeve which drivably connect the sleeve to the drive output shaft.

6. A method, according to Claim 5, including forming the retainer with a portion constituting the aforesaid member of the support means which engages the inner surface of the sleeve for the purpose of supporting the output end of the drive output shaft.

7. An auxiliary change-speed gearing, to be connected to a main change-speed gearing, including a drive input member to be connected to a drive output member of the main change-speed gearing, a tubular drive output member for said auxiliary changespeed gearing, said drive input member being arranged coaxially within said tubular drive output member, bearing means located between the outer surface of said tubular drive output member and a casing for said auxiliary change-speed gearing, and support means for rotatably supporting said drive output member of the main change-speed gearing including further bearing means in engagement with the inner surface of said tubular drive output member each side of a plane containing the first said bearing means.

8. An auxiliary change-speed gearing, connected to a main change-speed gearing, including a drive input member connected to a drive output member of the main changespeed gearing, a tubular drive output member for said auxiliary change-speed gearing, said drive input member being arranged coaxially within said tubular drive output member, bearing means located between the outer surface of said tubular drive output member and a casing for said auxiliary change-speed gearing, support means rotatably supporting said drive output member of the main change-speed gearing including further bearing means which engages the inner surface of said tubular drive output member each side of a plane containing the first said bearing means.

9. An auxiliary change-speed gearing according to Claim 8, in which the drive output member from the main change-speed gearing comprises a drive output shaft, which is drivably connected to the drive input member of the auxiliary change-speed gearing by means of a sleeve.

10. An auxiliary change-speed gearing according to Claim 9 and where the drive output shaft of the main change-speed gearing normally has its output end supported by a casing part which has been removed to enable the auxiliary change-speed gearing to be fitted, in which said output end is supported by means of a member of said support means which engages the inner surface of the sleeve adjacent the output end of said output

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. enable the servo 90 to be bolted to the casing portion 28. Conveniently, the servo includes a flexible diaphragm 97 connected to the pushrod by means of central clamping plates 99 arranged one each side of the diaphragm. The pushrod is rotatably connected to the clamping plates to enable the pushrod to rotate relatively to the servo, the diaphragm 97 sealingly engaging the periphery of the pushrod 92 between the two clamping plates 99. Instead of using a vacuum or other servo, the ratios may be manually selected through a suitable mechanical linkage. WHAT I CLAIM IS:

1. A method of drivably connecting an auxiliary change-speed gearing to a main change-speed gearing including drivably connecting a drive output member of said main change-speed gearing to a drive input member of said auxiliary change-speed gearing which is arranged coaxially within a tubular drive output member of the auxiliary change-speed gearing, rotatably supporting the drive output member of said auxiliary change-speed gearing in bearing means located between the outer surface of said tubular drive output member and a casing for said auxiliary change-speed gearing, and rotatably supporting said drive output member of the main change-speed gearing by support means including further bearing means which engages the inner surface of said tubular drive output member each side of a plane containing the first said bearing means.

shaft.

11. An auxiliary change-speed gearing according to Claim 10, in which the member of said support means is connected to the sleeve by splines.

12. An auxiliary change-speed gearing, according to Claim 10 or 11 and where the drive output shaft normally carries a spur gear held in place by a nut, which spur gear and nut have been removed to enable the auxiliary change-speed gearing to be connected to the main change-speed gearing, in which a screw-threaded retainer is screwed on to the drive output shaft in place of the nut and fits within the sleeve, the scrcw-threaded retainer including, or being arranged to co-operate with, abutment means abutting the axially inner ends of splines on the sleeve which drivably connect the sleeve to the drive output shaft.

13. An auxiliary change-speed gearing, according to Claim 12, in which the retainer has a portion constituting the aforesaid member of the support means which engages the inner surface of the sleeve for the purpose of supporting the output end of the drive output shaft.

14. An auxiliary change-speed gearing according to any of claims 8 to 13 in which the auxiliary gearing is lubricated by collecting the lubricant from an external reservoir, allowing the collected lubricant to lubricate the auxiliary gearing and subsequently to collect in a sump, and allowing the lubncant in the sump to reach a level determined by the position of an outlet duct through which the lubricant will return to said reservoir.

15. An auxiliary change-speed gearing, according to Claim 14, in which the lubricant is collected from the main change-speed gearing to which the auxiliary gearing is drivably connected and which constitutes said reservoir.

16. An auxiliary change-speed gearing, according to any of claims 7 to 15 and of the epicyclic kind, in which the lubricant is fed through a feed passage to a lubricant tube which extends axially of the epicyclic gearing and generally through the centre region so as to duct the lubricant to a distribution outlet from which the lubricant will travel by centrifugal force to lubricate the auxiliary change-speed gearing.

17. An auxiliary change-speed gearing according to any of Claims 7 to 16, including a servo having a reciprocable operating rod to be connected to ratio selector means of said auxiliary change-speed gearing, said operating rod being rotatably connected to diaphragm means in said servo to enable the operating rod to rotate relatively to the servo.

18. An auxiliary change-speed gearing, according to any of Claims 7 to 17 and of the epicyclic kind, including a sun gear wheel mounted for rotation on a spigot fast with a casing for the auxiliary change-speed gearing.

19. An auxiliary change-speed gearing, according to any of claims 7 to 18 and of the epicyclic kind, including planet gear wheels mounted for rotation on pins of a planet gear wheel carrier, each pin being formed with a recess or rebate at one end engageable with retaining means which is part of or arranged adjacent said planet gear wheel carrier to prevent rotation or axial displacement of each pin.

20. A method of drivably connecting an auxiliary change-speed gearing to a main change-speed gearing substantially as described herein with reference to the accompanying drawings.

21. An auxiliary change-speed gearing, to be connected to a main change-speed gearing, constructed and arranged substantially as described herein with reference to and as illustrated in Figure 1 or 5 of the accompanying drawings.

22. An auxiliary change-speed gearing, to he connected to a main change-speed gearing, constructed and arranged substantially as described herein with reference to and as illustrated in Figure 1 or 5 of the accompanying drawings.