Single-action freewheel clutch with substantially large central diameter

A single-action freewheel with an open diameter greater than 50 mm and with an inner and outer ring. The object is to provide an open central diameter of more than 500 mm while allowing high torques in a freewheel that can be made without consuming much material. The invention is charaterized by two or more rows (3 & 4) of shoes or jaws between the inner ring (1) and the outer ring (2) with normal clutching forces tht act more or less on one plane (13) or diameter, by one or more revolving webs (6) connected to the rings and extending between the rows, and by an activating mechanism (9) that approximately simultaneously tightens and loosens the shoes.

BACKGROUND OF THE INVENTION 
Many applications require an open central diameter, in which case the shaft 
will be hollow. Freewheels employed in power shovels, cranes, and 
turntables for example demand open central diameters of more than 500 mm. 
A double-action shoe-overriding freewheel is known from German AS 1 259 
151. It has two rows of shoes or jaws. Which row is engaged depends on the 
speed at which the engine and machinery are rotating. One drawback of this 
freewheel is that it cannot transmit extremely high stopping forces. The 
forces that occur normal to the shoes and act on the races during the 
clutching process are powerful enough to deform the rings, and the 
freewheel will no longer be able to function. Furthermore, the 
single-point stress that derives from the tilt of the races will destroy 
the shoes and races. 
SUMMARY OF THE INVENTION 
The object of the current invention is accordingly a single-action 
freewheel that will provide an open central diameter of more than 500 
while allowing high torques and that can be made without consuming much 
material.

The advantage of several rows of shoes acting simultaneously on one plane 
or diameter with revolving webs connected to one of the rings between them 
is that the transmitted clutching torque is the sum of the individual 
torques of each row of shoes. Thus, in contrast to a version with only one 
row of active shoes, each row needs to contribute only the fraction of the 
requisite friction represented by the inverse of the total number of rows. 
The result is a similar reduction in the normal forces applied by the 
individual shoes in inverse proportion to the number of rows. 
Orienting the rows of shoes with their normal forces toward one plane or 
diameter and with revolving webs that are connected to the rings extending 
between the rows ensures that the normal forces from the rows that act on 
opposite sides of the webs will include almost no bending forces. Another 
advantage is that the ring that accommodates the outer rows of shoes is 
expanded only by the fraction of overall normal forces that equals the 
inverse of the total number of rows. 
The advantage of providing the freewheel with its own housing is that it 
will not dictate the materials and heat treatments for example required 
for any components connected to it. 
One embodiment of the invention will now be described with reference to the 
drawing, which is a section through half a freewheel. 
DESCRIPTION OF THE PREFFERRED EMBODIMENTS 
The freewheel consists of two rows 3 and 4 of shoes and a roller bearing 5 
accommodated between an inner ring 1 and an outer ring 2. Outer ring 2 has 
a revolving web 6 that extends between rows 3 and 4. The shoes are secured 
in cages 7 and 8. An activating mechanism 9 simultaneously tightens and 
releases the shoes. The outer ring 2 in this embodiment is in one piece. 
Inner ring 1 on the other hand comprises four subsidiary rings 14, 10, 16, 
and 18, with jacketing ring 10 extending in the shape of a U around rows 3 
and 4 and preferably featuring hardened races 11. 
The matching races 12 in the web 6 on outer ring 2 are also hardened. The 
embodiment in question has two rows 3 and 4 of shoes. The clutching forces 
normal to both rows act on a plane 13, almost totally eliminating the 
interior forces on the web. The interior normal forces that spread 
jacketing ring 10 apart equal half the overall normal forces. One of the 
subsidiary rings that make up inner ring 1 is a ring 14 that secures cage 
7 over outer row 3. Securing ring 14 also has a sealing surface that is 
engaged by a lip on a seal 15 in outer ring 2. Another subsidiary ring is 
bearing ring 16, which screws onto jacketing ring 10. Bearing ring 16 
supports a race wire 17 that is part of roller bearing 5, a double 
slanted-roller row wire bearing. The other races on wires 17 rest against 
outer ring 2 and a toothed ring 18 that is also a component of inner ring 
1. The teeth 19 on ring 18 are on its inner surface. The individual 
subsidiary rings 14, 10, 16, and 18 that make up inner ring 1 are secured 
together with screws 20 and 21. Downstream machinery 23 is also secured to 
outer ring 2 with screws 22. Screws 24 and 25 secure upstream machinery 26 
to inner ring 1. While powerful torques are being maintained, the 
clutching forces deriving from rows 3 and 4 generate high spreading forces 
that tend to expand outer ring 2. To prevent this considerable expansion 
from endangering the function of the freewheel and to allow the employment 
of small inner and outer rings, the outer ring 2 in one preferred 
embodiment of the invention has a shoulder 27 and extends beyond the 
outside diameter of inner ring 1. Once the expanding forces are powerful 
enough to close gap 28, shoulder 27 will prevent inner ring 1 from 
expanding farther. Gap 28 must be maintained as narrow as possible. The 
rotation of the freewheel must of course not be impeded by friction 
between rings 1 and 2.