Knuckle Lock E42A & F41A

E42A - Part #: PN5500
F41A - Part #: PN5510


Poor quality and worn Knuckle Locks create issues with the coupling system

  • Excess wear can cause coupler slop and slack action, which may damage other components
  • Poor casting quality can create fit issues and prevent smooth operation of the coupler
  • Fit issues during assembly of couplers force carmen to grind surfaces on the lock and knuckle


Pennsy’s line of Knuckle Locks

To ensure universal fit Pennsy’s knuckle lock was designed using 3-D scans of a multitude of Locks, Couplers, and Knuckles found in interchange.

Lock dimensions and material properties are routinely checked to verify product conformity.

Pennsy’s proprietary material has greater wear resistance than the standard steel.


  • Due to Pennsy choice in material, the lock will not wear as quickly and will also prevent wear on the coupler and knuckle.
  • Thanks to Pennsy’s database of scanned coupling components and quality system, Pennsy avoids many of the fit issues found in the field.
  • Pennsy lock design and improved wear characteristics prevent coupler slop, which will help prevent premature failure of Knuckles and Coupler bodies
  • Pennsy’s Knuckle Locks are proudly made in the USA