- Join the NMRA
- About the NMRA
- Education
- Resources
- Community
Search NMRA.org
RP-22 HO Coupler Pocket
Designed by: Ken Mortimer
This sheet specifies the "Universal Coupler Pocket" for HO Scale. It has been designed to accommodate the greatest possible number of commercially available couplers of all types. All new couplers should be designed to mount in this pocket.
The coupler pocket may be made part of the car underbody or may be supplied seperately. It shall preferably be made of non-conducting material.
Where the coupler pocket is not made part of the underbody a flat area large enough to mount the separate coupler pocket shall be provided. This flat area shall be .470/.443" above the top of the rail and shall have two holes located .200/.205" from the car end .313/.318" apart, equally spaced from the car centerline, of suitable size for a #0 screw.
Where the coupler pocket is made part of the underbody the two .063/.068" holes shall be reduced to .047/.052", tap size for a #0 screw.
The hole marked "A" shall be of suitable size for a #2 screw. Where desired, a starting indentation only may be substituted for this hole.
Outside dimensions for the coupler pocket and its cover plate are not specified, these being items for the control of the individual supplier. Overall width of the coupler pocket shall be kept to a minimum to provide maximum practical truck swing.
Fillets and draft shall not exceed .005".
A coupler which cannot be accommodated by the coverplate shown shall be supplied with its own special coverplate for adaptation to this coupler pocket.
Projecting lugs on the unused side of the Cover may be removed.
A shim washer of suitable thickness may be used with older couplers of less than .073" shank thickness.