Device for connecting two shafts

The invention relates to a device for releasably connecting two shafts (1,2). It comprises two co-operating tapered clamping sleeves (5,6) and means (7,8,9) for relatively displacing the sleeves axially when the sleeves are separated by a pressure medium introduced between the tapered clamping surfaces. In order to make the device suitable for connecting two shafts with a certain distance between the shaft ends, the length of the sleeves is greater than the sum of the lengths of the portions of the respective shafts which are covered by the sleeves, and the bore diameter of the outer sleeve is greater than the outer diameter of the inner sleeve in an area (13) between the ends of the sleeves corresponding to the area between the shaft ends.

BACKGROUND AND SUMMARY OF THE INVENTION 
The instant invention relates to devices for releasably connecting two 
shafts, and particularly to shaft connection devices which include inner 
and outer clamping sleeves having cooperating, tapered, contacting 
surfaces, means for achieving relative axial displacement of the inner and 
outer sleeves, and means for supplying a pressure medium between the 
cooperating, tapered, contacting surfaces. 
Such devices are commonly used for connecting two shafts between which 
great forces and torques are transmitted. The lengths of the sleeves are 
chosen so that the sleeves enclose sufficiently long portions of the 
respective shafts in order to establish a desired clamping force between 
the inner sleeve and the respective shafts when the outer sleeve is 
mounted on the inner sleeve. The sleeves are made as short as possible for 
saving space and cost. The connected shafts are therefore usually placed 
so that the distance between the opposing shaft ends is as short as 
possible. 
Occasionally it is desirable, however, to maintain a certain distance 
between the shaft ends, for example in order to allow axial displacement 
of one shaft independent of the other during mounting or dismounting, or 
in order to give room for handling or indication members for adjusting 
means running through hollow shafts, e.g. devices for turning the blades 
of adjustable screw propellers, the connected shafts therewith 
constituting the propeller shaft. The present invention has an object to 
provide a device of the kind mentioned above, which device is suitable for 
connecting shafts with a certain distance between the shaft ends. 
According to the invention, this is achieved by a device which has the 
characterizing features recited in the appended claim 1. 
Such a device is especialy suitable for releasably connecting two shafts 
which are arranged at a distance from each other, and it can easily be 
designed to allow access to members which are attached to devices situated 
in axial bores in the shafts.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows two shafts 1, 2 which are interconnected by a device according 
to the instant invention. 
In order to increase the stiffness of the hollow shafts in the area 
surrounded by the device, rings 3, 4 of a material with a high strength 
and modulus of elasticity are arranged in the bores of the shafts. The 
device comprises an inner clamping sleeve 5 which surrounds the end 
portion of the shafts and which has a tapered outer surface, and an outer 
clamping sleeve 6 which surrounds the inner sleeve and which has a bore 
with a tapered surface corresponding to the tapered outer surface of the 
inner sleeve. Means for moving one of the sleeves axially in relation to 
the other are provided in form of an annular piston 7 arranged on threads 
at the end portion of the inner sleeve and in a recess 8 at the end 
portion of the outer sleeve, and a channel 9 for supplying a pressure 
medium to the recess. Channels 10, 11 for supplying a pressure medium 
between the cooperating tapered surfaces are provided in the outer sleeve. 
The channels 10, 11 are connected in a known manner to a pressure medium 
supply source so that when pressure medium is introduced through the 
channels, it penetrates the confronting contacting tapered surfaces of the 
sleeve members creating a film between these members which makes it 
possible to displace the sleeve members axially relative to one another 
during assembly and disassembly maneuvers. This well-known technique for 
displacing the sleeve members is similar to that described in the Blad et 
al U.S. Pat. No. 3,531,146 entitled PRESS OR SHRINK FIT JOINTS, issued 
Sept. 29, 1970 which patent is completely incorporated herein by 
reference. 
The length of the clamping sleeves is greater than the sum of the lengths 
of the portion of the respective shafts which are surrounded by the 
sleeves, the ends of the connected shafts being situated at a distance 12 
from each other. Thereby is achieved that one of the shafts can be 
displaced a distance towards the other shaft when the connection is 
released, which can be an advantage if e.g. one of the shafts is to be 
dismounted while displacement of the other is to be avoided, and the first 
mentioned shaft has to be drawn out from a fixed bearing position or the 
like during dismounting. 
In order to prevent the inner clamping sleeve from being permanently 
deformed radially inwardly in the area between the shaft ends by the 
pressure medium which is impressed between the clamping sleeves with a 
high pressure during the establishing of the connection, the bore diameter 
of the outer sleeve is greater than the outer diameter of the inner sleeve 
in an area 13 between the ends of the outer sleeve, which area corresponds 
to the area between the shaft ends, preferably increased by an area 
corresponding to the axial displacement of the outer sleeve on the inner 
sleeve when the connection is established. Therewith an annular space 13 
is obtained between the sleeves, surrounding the area of which the inner 
sleeve is not supported by any shaft. In this space the pressure medium 
will not be under pressure as long as the space is not completely filled, 
which normally never occurs. 
If, for example, an indication member visible outside the connecting device 
is desired, such as an indicator for the position of propeller blades 
adjustable by devices running through the hollow shafts, the sleeves can 
be provided with recesses 14, 15 through the sleeve walls in the area 
between the shaft ends, whereby for example an indicator connected to the 
adjusting device may extend through the recesses and move depending on the 
movements of the adjusting device. 
It is possible to provide two or more recesses around the respective 
sleeves, e.g. for symmetry reasons, whereby, of course, the pitch angles 
in the outer and the inner sleeve must be equal. 
The embodiment shown in the figure is arranged on hollow shafts and 
provided with recesses 14, 15 through the sleeves, but the invention is 
suitable also with massive shafts and with sleeves without recesses 
through the walls. The space 13 can be established either by an annular 
recess in the outer sleeve, as shown in the figure, or by an annular 
recess in the circumference of the inner sleeve. The recesses 14, 15 have 
an axial extension in order to allow axial movement of a member extending 
through the sleeves, but it is also possible to make e.g. round recesses 
through which a rotatable member may extend.