A landing gear for an aircraft, the landing gear comprising: a main strut having a socket; an articulated stay having a first end; and a cardan pin member pivotably attached to the first end of the articulated stay and further comprising a cylindrical post portion pivotably disposed in the main strut socket, characterized in that the cylindrical post portion defines a first annular recess disposed below the socket, such that the cardan pin member pivotably attaches the stay to the main strut in a cardan pin joint, and in that the landing gear further comprises: a ring-shaped retainer comprising a first semi-annular ring member and a second semi-annular ring member such that the first and second semi-annular ring members slidably engage the first annular recess cooperatively defining a radially outer surface, the ring-shaped retainer having a maximum transverse dimension, wherein the ring-shaped retainer defines an outwardly-open second annular recess; and an annular locking collar having a first inner diameter that is greater than the maximum transverse dimension of the ring-shaped retainer during installation such that the annular locking collar can be positioned over the second annular recess, and wherein the annular locking collar is configured to contract to a second inner diameter that is less than the maximum transverse dimension of the ring-shaped retainer by a change in temperature of the locking collar, such that the annular locking collar lockingly engages the second annular recess. a main strut having a socket; an articulated stay having a first end; and a cardan pin member pivotably attached to the first end of the articulated stay and further comprising a cylindrical post portion pivotably disposed in the main strut socket, characterized in that the cylindrical post portion defines a first annular recess disposed below the socket, such that the cardan pin member pivotably attaches the stay to the main strut in a cardan pin joint, and in that the landing gear further comprises: a ring-shaped retainer comprising a first semi-annular ring member and a second semi-annular ring member such that the first and second semi-annular ring members slidably engage the first annular recess cooperatively defining a radially outer surface, the ring-shaped retainer having a maximum transverse dimension, wherein the ring-shaped retainer defines an outwardly-open second annular recess; and an annular locking collar having a first inner diameter that is greater than the maximum transverse dimension of the ring-shaped retainer during installation such that the annular locking collar can be positioned over the second annular recess, and wherein the annular locking collar is configured to contract to a second inner diameter that is less than the maximum transverse dimension of the ring-shaped retainer by a change in temperature of the locking collar, such that the annular locking collar lockingly engages the second annular recess. characterized in that the cylindrical post portion defines a first annular recess disposed below the socket, such that the cardan pin member pivotably attaches the stay to the main strut in a cardan pin joint, and in that the landing gear further comprises: a ring-shaped retainer comprising a first semi-annular ring member and a second semi-annular ring member such that the first and second semi-annular ring members slidably engage the first annular recess cooperatively defining a radially outer surface, the ring-shaped retainer having a maximum transverse dimension, wherein the ring-shaped retainer defines an outwardly-open second annular recess; and an annular locking collar having a first inner diameter that is greater than the maximum transverse dimension of the ring-shaped retainer during installation such that the annular locking collar can be positioned over the second annular recess, and wherein the annular locking collar is configured to contract to a second inner diameter that is less than the maximum transverse dimension of the ring-shaped retainer by a change in temperature of the locking collar, such that the annular locking collar lockingly engages the second annular recess. a ring-shaped retainer comprising a first semi-annular ring member and a second semi-annular ring member such that the first and second semi-annular ring members slidably engage the first annular recess cooperatively defining a radially outer surface, the ring-shaped retainer having a maximum transverse dimension, wherein the ring-shaped retainer defines an outwardly-open second annular recess; and an annular locking collar having a first inner diameter that is greater than the maximum transverse dimension of the ring-shaped retainer during installation such that the annular locking collar can be positioned over the second annular recess, and wherein the annular locking collar is configured to contract to a second inner diameter that is less than the maximum transverse dimension of the ring-shaped retainer by a change in temperature of the locking collar, such that the annular locking collar lockingly engages the second annular recess.