Hydraulic wrench

A hydraulic wrench comprises an integrally cast housing having a first housing portion and a second elongated housing portion extending transverse to the first portion and forming a cylinder in which a piston is reciprocably mounted. A shaft extending transverse to the axis of the cylinder is turnably mounted in the first housing portion and carries at one end projecting beyond the housing an exchangeable socket for engaging a polygonal head of a threaded connector to be turned by the wrench. The shaft is turned in one direction during reciprocation of the piston over a ratchet mechanism interconnected between the piston rod and the shaft, whereby during such turning of the shaft and the connector engaged by the socket a force is created tending to turn the housing in the opposite direction. To counteract this force, a plate extending substantially parallel to the shaft is connected to the second housing portion and engages a fixed abutment adjacent the connector to be turned.

BACKGROUND OF THE INVENTION 
The present invention relates to hydraulic wrenches and more particularly 
to hydraulic wrenches which can be advantageously used for tightening and 
loosening threaded connectors such as nuts mounted on bolts in which a 
plurality of nuts which are closely adjacent to each other have to be 
tightened or loosened and in which the overhead clearance for applying a 
wrench to the nuts is rather limited, which would make it impossible to 
use a standard air or impact wrench. 
More specifically, the present invention relates to hydraulic wrenches in 
which the force created during turning of a threaded connector in one 
direction and tending to turn the whole wrench in the opposite direction 
is taken up by means connected to the wrench and adapted to engage a fixed 
abutment adjacent to the threaded connector to be turned. 
Such a hydraulic wrench is known in the art, as for instance disclosed in 
my U.S. Pat. No. 4,027,561. 
This known hydraulic wrench has, however, certain disadvantages in that it 
comprises a relatively great number of parts so that this known hydraulic 
wrench is rather expensive to manufacture. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a hydraulic wrench 
which can be used for tightening or loosening threaded connectors which 
are closely adjacent to each other and in which the overhead space for 
applying a wrench is limited. 
It is a further object of the present invention to provide a hydraulic 
wrench by means of which a large constant torque can be applied to the 
threaded connector which has to be tightened or loosened. 
It is an additional object of the present invention to provide for a 
hydraulic wrench of the aforementioned kind which can be easily adapted 
for use of threaded connectors of different size. 
It is also an object of the present invention to provide a hydraulic wrench 
of the aforementioned kind which is compacter than the known hydraulic 
wrench mentioned above so that it will stand up perfectly under extended 
use. 
With these and other objects in view, which will become apparent as the 
description proceeds, the hydraulic wrench according to the present 
invention mainly comprises a housing having a first portion and an 
elongated second portion integral with said first portion and extending 
transverse to the latter and forming a cylinder, piston means 
reciprocatable in said cylinder, shaft means having an axis extending 
transverse to that of the cylinder and being turnably mounted in the first 
housing portion with an end portion of the shaft means projecting 
outwardly from the housing, a piston rod connected at one end to the 
piston means, at least one drive lever mounted in the region of one end 
turnable about the axis of the shaft means and pivotally connected at its 
other end to the other end of the piston rod, a ratchet wheel fixed to the 
shaft means for rotation therewith, a ratchet pawl on the drive lever and 
engaging the ratchet wheel to rotate the shaft means upon reciprocation of 
said piston means in the cylinder, exchangeable socket means mounted on 
the end portion of the shaft means for engaging a polygonal head of a 
threaded connector for turning the latter, whereby during such turning of 
the threaded connector in one direction a force is created tending to turn 
the housing about the axis of the shaft means in the opposite direction, 
and means connected to the second housing portion and extending laterally 
spaced from the shaft means substantially parallel thereto and adapted to 
engage a fixed abutment adjacent to the threaded connector to be turned 
for counteracting the aforementioned force. 
The piston means preferably comprises an annular piston slidably mounted in 
the cylinder and a tubular member having an end portion in the cylinder 
and projecting from this end portion into the first housing portion, in 
which the annular piston is coaxially mounted on the aforementioned end 
portion of the tubular member and the housing includes at the junction of 
the first and second housing portion an annular projection in which a 
portion of the tubular member is slidably guided. 
The piston rod may be pivotally mounted at the aforementioned one end in 
the end portion of the tubular member, but on the other hand, the piston 
rod may be fixedly connected at one end to the piston means, whereas the 
other end of the piston rod may be provided with a pair of trunions 
projecting to opposite sides of the piston rod and being engaged in 
elongated slots formed in a pair of drive levers arranged in the first 
housing portion to opposite sides of the ratchet wheel. 
The second housing portion has a flat face beyond which the first housing 
portion projects and the means for counteracting the aforementioned force 
preferably comprises a plate removably connected to the second housing 
portion and abutting with a side face thereof against the aforementioned 
flat face of the second housing portion. 
Preferably, the second housing portion is provided at opposite sides 
thereof, adjacent the aforementioned flat face, which a pair of outer 
ridges extending substantially parallel to the axis of the cylinder and 
forming a groove therebetween and the plate for counteracting the force 
has preferably a transverse portion engaged in the aforementioned groove 
and extending about one of the ridges. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawing, and more specifically to FIGS. 1-3 of the 
same, it will be seen that the hydraulic wrench according to the present 
invention comprises a housing 1 having a first housing portion 2 and an 
elongated second housing portion 3 extending transverse, that is 
substantially normal to the first housing portion and being formed with an 
elongated bore 4 therethrough forming a cylinder having an axis 4'. Piston 
means 5 are slidably guided in the cylinder bore 4 for reciprocation along 
the aforementioned cylinder axis 4'. The piston means 5 comprise a tubular 
member 6 having an end portion 6' located in the cylinder bore 4 and 
projecting from this end portion 6' into the interior of the first housing 
portion 2. The end portion 6' of the tubular member 6 has inner and outer 
peripheral surfaces respectively of a smaller diameter than the remainder 
of the tubular member 6 to form an outer peripheral shoulder 6" and an 
inner peripheral shoulder 6"'. The piston means comprises further an 
annular piston 7 placed on the reduced diameter end portion 6' coaxially 
therewith and abutting against the outer shoulder 6". The annular piston 7 
is preferably provided on the outer peripheral surface thereof with a pair 
of annular grooves 7' in which sealing rings 8 are located. The housing 1 
is provided at the junction of the first housing portion 2 and the second 
housing portion 3 with an annular inwardly extending projection 9 in which 
the projecting portion of the tubular member 6 is guided. In this way the 
piston means 5 is guided at two axially spaced portions thereof for 
reciprocation along the axis 4' of the cylinder bore 4. A piston rod 10 
extends in longitudinal direction through the tubular member 6 of the 
piston means 5 and the substantially spherical end portion 10' of the 
piston rod 10 is pivotally connected to the end portion 6' of the tubular 
member 6. For this purpose a first seat member 11 is mounted in the 
interior of the tubular end portion 6' abutting against the inner shoulder 
6"'. This seat portion has an inner surface 11' in the form of a spherical 
zone and engages a spherical piston rod end portion 10' on the left side 
of the latter, as viewed in FIG. 1, whereas the opposite side of the 
spherical piston rod end portion 10' is engaged by an opposite seat 
portion 12 having an inner part spherical surface 12' and being threadedly 
connected to the inner surface of the end portion 6' of the tubular member 
6 of the piston means 5. The second seat portion 12 is preferably provided 
with a pair of transversely spaced blind bores 12" for engagement with a 
tool to facilitate threading of the second seat portion 12 into the end 
portion 6'. The other end 10" of the piston rod 10 has a reduced diameter 
and is engaged in a bore 13' extending along the axis 4' of a connecting 
member 13. The connecting member 13 is formed with a second bore 13" 
extending normal to the axis 4'. The connecting member 13 is fixedly 
connected to the end 10" of the piston rod 10 by a screw 14 extending 
through aligned bores in the connecting member 13 and the end 10" of the 
piston rod. 
The first housing portion 2 has a pair of transversely spaced parallel side 
walls 2', as best shown in FIG. 2, each of which is formed with a circular 
opening 2" therethrough transversely spaced from the cylinder axis 4'. A 
pair of sleeves 15 are respectively turnably mounted in the openings 2" 
and each of the sleeves 15 having at the inner end, located inwardly of 
the respective wall 2', an annular flange 15' of a larger diameter than 
the sleeve portions in the openings 2". Each of the sleeves 15 is formed 
with an inner substantially square opening therethrough in which a shaft 
16 is tightly engaged projecting with one end portion 16' beyond the 
respective side wall 2'. An exchangeable socket 17 is releasably connected 
by a set screw of the like, not shown in the drawing, to the projecting 
end portion 16' of the shaft 16. The socket 17 is a standard socket formed 
at the outer end thereof with a hollow portion constructed to engage the 
hexagonal head of a connector to be tightened by the wrench. By exchanging 
the socket 17 with a socket of different size connectors of different size 
may be tightened and/or loosened by the wrench of the present invention. 
In order to turn the square shaft 16 and the socket 17 connected thereto 
during the reciprocation of the piston means 5 in the cylinder bore 4, the 
wrench includes further a ratchet wheel 18 fixed to the square shaft for 
rotation therewith between the flange portions 15' of the sleeves 15 and a 
pair of drive levers 19 provided in the region of one of the ends thereof 
with bores 19' in which the flange portions 15' of the sleeves 15 are 
respectively lodged and in the region of the other ends thereof with bores 
19" coaxially arranged with the bore 13" of the connecting member 13. A 
pivot pin 20 extends through the aligned bores 13" and 19". The 
arrangement includes further a drive pawl 21 having a pair of prongs 21' 
respectively sandwiched, as best shown in FIG. 2, between the drive levers 
19 and the connecting member 13 and the drive pawl 21 has a lower end 21" 
adapted to engage the teeth 18' of the ratchet wheel 18. A leaf spring 22 
connected to one of the drive levers 19 engages the drive pawl 21 for 
keeping the latter in engagement with a respective tooth 18' of the 
ratchet wheel 18. A needle bearing 23 may be provided in the bore 13" of 
the connecting member 13 and engaging the peripheral surface of the pin 
20. The arrangement includes further a holding pawl 24 pivotally mounted 
at one end in the housing portion 2 and adapted to engage with the free 
end thereof a tooth 18' of the ratchet wheel to prevent movement of the 
latter during the return stroke of the piston means 5. A spring 26 wound 
about the pivot pin 25 of the holding pawl 24 engages with opposite ends 
the holding pawl 24 and a portion of the housing 1 in the manner as shown 
in FIG. 1 to keep the holding pawl 24 in engagement with a respective 
tooth of the ratchet wheel 18. 
The wrench includes further a valve housing 27 connected to the free end of 
the housing portion 3 by screws or the like and carrying in the interior 
thereof valve means of known construction not forming part of the present 
invention and therefore not shown in the drawing, for alternatingly 
feeding pressure fluid into the cylinder bore 4 to opposite sides of the 
annular piston 7 through the fluid passage 28 and another not shown in the 
drawing, respectively communicating with the cylinder bore 4 in the region 
of opposite ends of the latter. A rod 30 coaxially arranged with the axis 
4' of the cylinder bore 4 is threadingly connected at one end to the seat 
member 12 and on the other end to the valve body, not shown in the 
drawing, of the valve means located in the valve housing 27. A pair of 
connectors 31 and 32 projecting laterally from the valve housing 27 serve 
to connect the valve located therein to a source of pressure fluid and a 
tank, not shown in the drawing. 
In FIG. 1 the annular piston 7 is shown in an intermediate position in the 
cylinder bore 4 located midways between two end positions. It will be 
noted that in this position, as shown in FIG. 1, the piston rod 10 
coincides with the axis 4' of the cylinder bore 4 and a line a connecting 
the center of the pin 20 with the center of the square shaft 16 extends 
normal to the aforementioned axis of the piston rod 10 so as to provide 
the maximum torque to the square shaft. During reciprocation of the piston 
means 5 between the two end positions thereof the center of the pin 20 
will move along an arc b having its center at the center line of the 
square shaft 16 so that the torque applied to the latter will vary only 
slightly. During reciprocation of the piston means 5 from a right end 
position, as viewed in FIG. 1, to a left end position, that is during the 
active stroke of the piston means 5, the ratchet wheel will be turned in 
the direction of the arrow X by engagement of the free end portion 21' of 
the drive pawl 21 with a respective tooth 18' of the ratchet wheel 18. 
During the return stroke of the piston means 5, the ratchet wheel 18 will 
be prevented to move in the opposite direction by the holding pawl 24 
engaging a corresponding tooth of the ratchet wheel 18. During turning of 
the shaft 16 and the socket 17 connected thereto and corresponding 
tightening or loosening of a threaded connector engaged in the socket 17, 
a force will be created tending to turn the housing 1 in a direction 
opposite to the direction indicated by the arrow X. 
To counteract this force a plate 33 is connected to the second housing 
portion 3 abutting with a side face thereof against a flat side face 34 of 
the second housing portion 3 and having at one end a portion 35 extending 
transverse to the plate 33 and engaging into a groove 36 located between 
two ridges 37 and 38 extending parallel to the longitudinal axis 4' of the 
cylinder bore 4 adjacent to the flat face 34. The transverse portion 35 is 
connected by one or a plurality of screws 39 to the second housing portion 
3. As shown in FIG. 3 the housing portion 3 is also provided at the other 
side thereof with a corresponding groove 36' located between two ridges 
37' and 38' so that the position of the plate 33 together with that of the 
projecting shaft portion may be reversed. The plate 33 is arranged to abut 
with the outer side face 33' thereof against a stationary abutment, which 
may be for instance a nut N adjacent to the threaded connector to be 
tightened so as to counteract the force tending to turn the wrench in a 
direction opposite to the direction indicated by the arrow X during 
tightening or loosening a threaded connector engaged in the socket 17. 
The wrench includes further a curved sheet metal cover 40 connected to the 
first housing portion 2 by screws as shown in FIG. 1 to prevent dust or 
foreign particles to penetrate into the interior of the housing. 
FIG. 4 illustrates a modification of the above-described hydraulic wrench 
illustrated in FIGS. 1-3. The modification shown in FIG. 4 differs from 
the abovedescribed modification illustrated in FIGS. 1-3 mainly in that a 
piston rod 10a is not pivotally mounted on its right end between the two 
seat portions 11 and 12, but in this modification, the right end 10a' of 
the piston rod 10a is screwed into a plug 12a which in turn is screwed 
into the right end of the tubular member 6. The left end 10a" of the 
piston rod 10a is again connected by a pin 14 to the connecting member 13 
which carries in a bore thereof extending normal to the axis c of the 
piston rod 10a a pin 42 which is engaged at opposite ends in elongated 
openings 41 respectively formed in the upper region of a pair of drive 
levers 19a, only the rear one being shown in FIG. 4. These elongated 
openings 41 extend substantially in the direction of the axis d of the 
drive levers 19a. In this construction the drive levers 19a have to be 
longer than the drive levers 19 shown in FIGS. 1 and 2 since the drive 
pawl 21 is carried on a separate pin 43 extending parallel to the pin 42 
through bores in the drive lever located laterally spaced from the 
elongated openings 41. In this construction the center of the pin 42 will 
move during reciprocation of the piston means 5 between its two end 
positions along a straight line between the points L and M located along 
the center line c of the piston rod 10a. It will therefore be evident that 
the torque applied to the square shaft 16 during operation of the wrench 
will remain constant which is a decisive advantage of the modification 
shown in FIG. 4 as compared with the first-described modification in which 
the torque will vary slightly. Of course, the modification shown in FIG. 4 
includes also a plate 33 connected to the second housing portion 3 in the 
manner as described in connection with the embodiment shown in FIGS. 1-3 
for counteracting a force tending to turn the housing 1 of the wrench in a 
direction opposite to the direction a threaded connector engaged by the 
socket 17 is turned during the operation of the wrench. 
In both modifications the second housing portion forms a torque reaction 
box. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
hydraulic wrenches differing from the types described above. 
While the invention has been illustrated and described as embodied in a 
hydraulic wrench provided with means for counteracting a force tending to 
turn the hydraulic wrench during operation in a direction opposite to the 
direction a threaded connector is turned by the wrench, it is not intended 
to be limited to the details shown, since various modifications and 
structural changes may be made without departing in any way from the 
spirit of the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can by applying current knowledge 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.