Torque applicator

A double-acting piston and a rotatable torque applicator stem are mounted in a torque applicator housing such that the stem is actuated by the double-acting piston. A coupling member is non-movably mounted on the stem and another coupling member is mounted for axial movement thereon, each coupling member including teeth alternately engageable with the teeth of the other coupling member. The movable coupling member includes a radial arm having a free end cooperating with the double-acting piston to cause a reciprocating rotary movement of the axially movable coupling member with respect to the stem. Pressure is alternately applied on one face and the opposite face of the movable coupling member in synchronization with the actuation of the double-acting piston.

BACKGROUND 
1. Field of the Invention 
The present invention relates to a torque applicator comprising a housing 
in which is disposed a rotatable torque applicator stem actuated by a 
hydraulic or pneumatic double-acting piston to apply an intermittent 
torque on bolts, nuts etc. A torque applicator of this kind is known from 
Norwegian Patents 115.991 and 136.609. The present invention is a further 
development of these known torque applicators. 
2. Prior Art and Summary of the Invention 
The torque applicator of the present invention differs from the prior art 
in that the two members of a claw coupling are mounted on the rotatable 
torque applicator stem, one coupling member being fixed and non-movably 
mounted on the stem, and the other coupling member being mounted for axial 
movement on the stem. The movable coupling member is provided with a 
radial arm the free end of which co-operates with the double-acting piston 
to cause a reciprocating rotary movement of the axially movable coupling 
member on the applicator stem. 
The movable coupling member is adapted to be moved axially on the torque 
applicator stem by hydraulic or pneumatic pressure on one and the other, 
respectively, axial end surfaces of the coupling member, in time with the 
actuation of the piston, the coupling member thereby being brought into 
and out of engagement with the fixed coupling member.

DETAILED DESCRIPTION 
The drawing shows a pressure activated torque applicator comprising housing 
1 in which are disposed a rotatable torque applicator stem 2 and its 
torque providing devices. The stem 2 is actuated by a hydraulic or 
pneumatic double-acting piston 3. A claw coupling is provided between the 
piston 3 and the stem 2, the coupling comprising a coupling member 4 being 
fixedly mounted on the stem 2 and a coupling member 5 being axially 
movable on the stem 2 and being rotatable with respect to the stem 2 when 
not in engagement with the fixed coupling member 4. The movable coupling 
member 5 carries a substantially radial arm 6 which at its free end 
co-operates with the piston 3. FIGS. 2 and 3 show two examples of how the 
arm 6 may cooperate with the piston 3. 
In the embodiment shown in FIG. 2 the piston 3 is provided with an oblique 
end surface, and the arm 6 carries a roller or the like 7 at its free end 
for rolling against the oblique surface of the piston 3. To ascertain the 
return movement of the arm 6 upon the return stroke of the piston 3, a 
compression spring 8 is provided for action between the arm 6 and a wall 
of housing 1. 
In the embodiment shown in FIG. 3 the piston 3 is provided with an oblique 
slot 9, and the arm 6 carries a pin or the like 10 at its free end which 
pin extends into the slot 9. In this embodiment there is no need for a 
returning spring corresponding to the spring 8 in FIG. 2. 
In operation, fluid under pressure is passed alternately into the pressure 
chamber on the one side and on the other side, respectively, of the piston 
3, the pressure chamber on only one side of the piston being shown in the 
drawing, to move the piston reciprocatingly towards and away from the 
applicator stem 2. Fluid under pressure for bringing the piston 3 away 
from the stem 2, i.e. towards the right on the drawing, enters the 
pressure chamber through a passage 11 (FIGS. 1 and 2). Through a passage 
12 this fluid is also passed in below the lower face of the movable 
coupling member 5 to lift the same from the fixed coupling member 4 to 
allow it to rotate freely with respect to the fixed coupling member and 
with respect to the applicator stem 2 under the action of the spring 8 
(FIG. 2) or through the co-action between the pin 10 and the slot 9 (FIG. 
3). When pressurized fluid is brought to act on the opposite (right hand) 
end face of the piston to move the piston towards the applicator stem 2, 
pressurized fluid is passed through a passage 13 (FIG. 1) to a restricted 
space above the coupling member 5 to force the same into engagement with 
the fixed coupling member 4. Upon co-action between the piston end surface 
and the roller 7 or between the piston slot 9 and the pin 10, the arm 6 
and the movable coupling member 5, and thus also the fixed coupling member 
4 and the actuator stem 2, are rotated clockwise as seen in FIGS. 2 and 3. 
The co-action faces of the coupling members 4 and 5 may be in the form of 
claws or in the form of gear rims, and in the embodiment shown in FIG. 1 
the gear rims are conical, but even crown gear rims are feasible. 
The embodiments of FIGS. 1 to 3 show the applicator having a stem 2 
extending from both sides of housing 1, whereby the applicator may be used 
for tightening and untightening operation without changing the sense of 
rotation of the stem. In an alternative embodiment, not shown, in which 
the stem extends to only one side of the housing, the sense of activation 
of the coupling with respect to the sense of activation of the piston may 
be changed, whereby the sense of rotation of the stem may be changed at 
will. When using this alternative embodiment, the coupling (4,5) and thus 
the entire applicator may be made "slimmer".