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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Provisional specification detailing improvements to change-speed gearing mechanisms.

Identifier  ExFiles\Box 136\4\  scan0161
Date  20th October 1932
  
2 402,924
but to so engage its slot at one time the
remaining link bars resting on the peri-
phery of the shaft. A neutral position is
provided in which no link can engage
5 its slot.
The disengaging camshaft is suitably
coupled to the engine clutch pedal and the
selector shaft is suitably connected to a
hand controlled lever. The selector
10 shaft is preferably turned through the
medium of a toothed rack or quadrant
that meshes with a pinion on the selector
shaft. Flanges may separate the slots in
the selector shaft.
15 Assuming the top speed of a four-speed
gear to be engaged and it is desired to
change down to third speed the lever con-
trolling the selector shaft is moved to
bring the third speed slot in the shaft to
20 its top position. The corresponding link
bar will slightly engage the slot and the
end of the bar will rest on the arm or
wing of the shift lever that has to func-
tion to make the gear change. This
25 operation may be made at any time in
advance of the actual gear change.
To effect the gear change the engine
clutch pedal is depressed and this causes
the disengaging camshaft to give an axial
30 movement to the peg and shift fork of
the top speed and so disengage that gear.
The same movement of the camshaft slides
the link bars outwards and as the third
speed link bar is engaged with its slot in
35 the selector shaft and can drop still fur-
ther into the slot it falls over the end of
the shift lever arm or wing at the end of
its outward movement the peg or equiva-
lent on the end of the link bar then engag-
40 ing the arm or wing. By releasing the
engine clutch pedal the camshaft returns
to its normal position and in doing so
gives an inward movement to the link
bar causing the latter to give a pull on
45 the shift lever that slides the shift fork
axially to engage the third speed member.
The camshaft may be returned to its
normal position by means of a separate
spring or its return may be effected by
50 means of the clutch pedal spring or clutch
spring or any combination of these.
Clearances and neutral channels may be
provided on the camshaft where desirable.
Locating plungers or pawls may also be provided to locate the various parts of 55
such of these as desired.
My invention may be varied in its
arrangement by pivoting the link bars on
the shift lever and adapting their free
ends to engage studs or equivalent on the 60
camshaft or alternatively by providing a
peg on each link bar that can be moved
by a cam face on the link bar or on a
ring attached thereto. When desirable
the camshaft may engage with a peg on 65
the shift lever instead of on the shift
fork.
If desired the camshaft itself may be
coupled by suitable cranks or the like to
the loose member of the engine or equiva- 70
lent friction clutch as such an arrange-
ment may be advantageous in the case of
small gears such as are used on motor
cycles and similar light vehicles.
Preferably the gear change is effected 75
before the engine clutch re-engages and a
dash-pot or equivalent may be provided
to retard the re-engagement of the clutch
members.
My invention may be applied to motor- 80
cycle gearboxes in substantially the same
manner as described and adapted to either
hand control or foot control of the engine
or equivalent friction clutch.
My invention can be employed with 85
change-speed gears using the synchro-
mesh form of gear changing in which
friction cones or the like are employed as
means of synchronising the speeds of the
members to be engaged prior to their posi- 90
tive engagement and also with change-
speed gears employing a free-wheel or
other coupling between the gear shaft
and the propeller shaft.
My invention can also be employed with 95
any form of hydraulic or automatic clutch
or coupling.
Although for convenience of description
my invention is herein described as being
arranged above the gear members it is 100
within the scope of my invention to
arrange it in any other position in the
gearbox that is suitable for its operation
as described.

Dated the 20th day of October, 1932.
A.{Mr Adams} ALLTREE.

PROVISIONAL SPECIFICATION.
No. 30,969, A.D. 1932.
Improvements in and relating to Change-speed Gearing.
105 I, ARTHUR ALLTREE, Rydal Dene, in the County of Lancaster, British sub-
Pilling Lane, Preesall, near Fleetwood, ject, do hereby declare the nature of this

402,924 3
invention to be as follows :—
My invention relates to improvements
in pre-selector gear change mechanism for
use with change-speed gearing of the type
5 in which certain elements or members of
the gear are positively engaged with
other elements or members or moved into
mesh therewith to effect a gear change,
said mechanism being applicable to any
10 form or arrangement of this class of gear-
ing as used on motor cars motor cycles or
other motor vehicles.
According to my invention a bar is
arranged parallel with the gear shaft
15 and upon this bar shift forks that are
adapted to slide those members of the
gear that are moved to effect gear changes
are suitably mounted. A peg is provided
on each shift fork and this peg is adapted
20 to be engaged by the forked end of a
shift lever which has its other end pivoted
to a convenient part of the gearbox
casing.
A camshaft is mounted parallel with
25 the shift forks bar and this camshaft is
formed with cam faces that when the
camshaft is partially rotated will dis-
engage any gear that may be engaged
moving the shift fork corresponding with
30 such gear into its neutral position the
cam face acting on the peg. The cam-
shaft is provided with a cam for each gear
change and reverse and its primary object
is to ensure that no gear is engaged at
35 the moment a gear change is being made.
As an alternative to the use of a single
peg on the shift fork I may provide two
such pegs one for the shift lever and the
other for the camshaft.
40 In a further alternative I may provide
a second shift lever adapted to engage
with the single peg on the shift fork or
with the second peg. This second shift
lever is provided with a peg that engages
45 with and can be moved by the camshaft
to cause the second shift lever to slide
the shift fork into its neutral position.
The second shift lever is mounted in sub-
stantially the same manner as the first
50 shift lever but preferably on the opposite
side of the gearbox.
In any arrangement the camshaft may
be formed with recesses to receive the pegs
when the camshaft is in its normal or
55 inoperative position one recess to receive
the peg in its neutral position and an-
other recess to receive the peg in its en-
gaged position the object being to keep
the shift forks and gear members corre-
60 sponding therewith in their neutral or
engaged positions as the case may be.
When one shift fork has to move axially
in two directions to effect two gear
changes a single neutral recess is provided
65 with a recess on each side of it corre-sponding with the engaged position of
each gear change.
Rollers may be mounted upon any of
the pegs to facilitate operation or reduce
wear. 70
Link arms or bars are pivoted to the
camshaft one link bar for each forward
speed and one for reverse and these link
bars are adapted to be engaged with suit-
able arms or wings provided on the shift 75
levers. Guides may be provided to take
any side stresses on the link bars and a
slotted plate or plates secured to the gear-
box casing may serve for this purpose the
link bars sliding in the slots. 80
A selector shaft arranged parallel with
the camshaft is employed to determine
which link bar shall be engaged the
selector shaft being formed with slots
equal to the number of link bars and deep
enough to permit the link bars to engage 85
with the shift levers the slots being so
spaced around the shaft that when the
latter is rotated each slot in turn comes
into a position in which its link bar can
engage with the corresponding shift lever. 90
A neutral position is provided in which
no link bar can engage with a shift lever.
The disengaging camshaft is suitably 95
coupled to the engine or equivalent clutch
pedal and the selector shaft is suitably
connected to a hand controlled lever the
selector shaft preferably being turned
through the medium of a toothed rack or
quadrant that meshes with a pinion on 100
the selector shaft. When desirable the
camshaft may be operated by means of
a hand lever or pedal other than the
clutch pedal.
A spring or springs may be employed 105
to return the camshaft to its normal posi-
tion after use one end of the spring being
secured to the camshaft or to an arm or
lever thereon and the other end anchored
to the gearbox casing. 110
As an alternative to engaging with a
peg or pegs on the shift forks the first
or second shift levers may be adapted to
engage slots formed in the shift forks
either separate slots or a slot common 115
to each pair of levers.
If desired the selector shaft may be
arranged at or near the free ends of the
link bars and in such an arrangement a
middle part of each link bar may be
adapted to engage with its shift lever. 120
Alternatively each link bar may be
pivoted at about its middle to the cam-
shaft thus providing two free ends one of
which is controlled by the selector shaft 125
and the other adapted to engage with the
shift lever.
In use partial rotation of the camshaft
ensures that no gear is engaged and the
same movement engages a link bar with 130
  
  


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