Connection between a rod and crosshead in a reciprocating compressor
A connection between a rod and crosshead in a reciprocating compressor includes threaded units, an anti-rotational securing device and axial positioning elements, wherein the threaded units has a first inner lock nut, provided with an inner thread onto which there is screwed a threaded end portion of the rod and provided with two outer threads with a different diameter, one of which is for connection to the left-handed anti-rotational securing device, and the units also include a second outer lock nut in the inner diameter of which a thread is provided.
1. A connection between a rod and a crosshead in a reciprocating compressor comprising:
threaded units,
an anti-rotational securing device and
axial positioning elements connecting the crosshead and the rod, wherein the threaded units include a first inner lock nut and a second outer lock nut, the second outer lock nut further includes a threaded inner diameter to receive the first inner lock nut, wherein the first inner lock nut includes an inner thread onto which there is screwed a threaded end portion of the rod and the first inner lock nut includes outer threads with different diameters, wherein one of the outer threads threadably connects to the anti-rotational securing device, the other one of the threads threadably connects to the second inner lock nut which is inserted into one of the positioning elements.
2. A connection as in claim 1 , wherein said anti-rotational securing device comprises a securing ring nut for the lock nuts, wherein an inner diameter of the securing ring nut includes a left-handed thread to receive a left-hand thread of the one of the outer threads of the first inner lock nut; the connection further includes an element to secure the rod includes a cylindrical end portion provided with a left-handed thread for engagement with a countersunk threaded hole, wherein the hole is provided in a circular head surface of the said rod.
3. A connection as in claim 2 , wherein said securing ring nut includes an end lip foldable inside a seat provided in one of said axial positioning elements.
4. A connection as in claim 2 , wherein said element for securing the rod includes an outer limb foldable into at least one aperture in a lateral annular surface of the first lock nut.
5. A connection as in claim 1 , wherein said axial positioning elements comprise a positioning ring for connection to said rod and a flange for connection to the crosshead.
6. A connection as in claim 5 , wherein said flange comprises a sleeve to contain the rod, the lock nuts, and a plate for connection to the crosshead.
7. A connection as in claim 5 , wherein said positioning ring has a frusto-conical mouth surface which is complementary to a stop surface of the rod, and the mouth surface is inclined by an angle (α) relative to an axis of the rod.
8. A connection as in claim 6 , wherein said positioning ring has an inner diameter equal to a maximum diameter of a centering portion of the rod.
9. A connection as in claim 5 , wherein said first inner lock nut and the second outer lock nut each have an end cylindrical section having a diameter for engagement in cylindrical seats provided in the inner diameter of the flange.