Type F interlocking couplers are equipped with the F design head end and the F design shank and butt end. Incorporated into the F design are several features that are not available in the Types E and E/F designs. These added features include:

  1. Frontal interlocking wing pocket and lugs that interlock with any mating interlocking coupler. These safety features help maintain the couplers and derailed cars in alignment to assist in preventing over-turning and telescoping of the cars.
  2. A frontal bottom support shelf is standard on all F couplers to prevent a mating pulled out coupler from falling to the roadbed and thereby becoming a hazard.
  3. A total of only 3/8 inches of free contour slack exists between two new F interlocking couplers; as opposed to 25/32 inches for two new Type E or Type E/F mated couplers. The result is an improvement in train handling actions.
  4. Reduction in wear on head surfaces result in extended service life; due to control of vertical interface movements and less free contour slack
  5. Buff loads are distributed through the central column of the F interlocking coupler.
  6. When provided, the shank butt alignment shoulders assist in keeping the couplers centered and cars aligned under heavy buffing actions and slack run-in.
  7. The vertical pin connection makes a more efficient assembly than possible with a crosskey.
  8. Coupler locklift assembly provides a telltale visual means for determining that the coupler is securely locked.
  9. A three-way anticreep feature prevents accidental uncoupling of the rotary bottom operating Type F coupler.

To meet varied service equipment arrangement needs, Type F couplers may be equipped with variant compatible shank designs and special features or fittings. For purposes of identification, each different coupler design is indicated by the assignment of a Catalog Number or ID Number. Modifications to existing designs are indicated by the assignment of suffix letters to coupler Catalog Numbers or ID Numbers.

Type F couplers are furnished with bodies, knuckles, and locks of quenched and tempered Grade E steel.

Grade E material is identified by the letter E at the end of the item Catalog Number or ID Number.

Specific design Type F couplers have been adopted by the AAR as Standards and Optional Standards for certain types of car service usage, or to suit a given car geometry. These couplers are protected in Interchange Service against improper replacement under AAR Rule 18. Certain variables of these coupler designs, having Special Features, have been approved by the AAR and assigned coded ID Numbers. These Specials are covered by Rule 72 for replacement.

It is most essential that coupler effective length (coupling line to rear pivot point) and shank design are compatible with the other items of the car draft assembly. Thus, couplers having non-AAR approved shank designs (including lengths) are not interchangeable on cars.

All Type F couplers have the Number 10-A contour at coupler mating lines. This contour includes all external vertical faces of the knuckle and body front faces and guard arm faces that meet and engage with an opposing coupler to couple adjoining cars. Type F couplers will couple with all other Type F couplers in Interchange Service.

Currently, practically all freight cars in the United States are equipped for bottom operation couplers. Therefore, unless specifically ordered as Top Operating, Type F couplers will have the top locklift hole cast closed and be fitted as Single Rotary Bottom Operating.

All of the Standard operating parts are interchangeable from one Type F coupler to another; except when the locklift arrangement precludes change in design of the locklift assemblies. The Type F operating parts are designed so that they will not fit into other types of couplers, except as listed:

C10 Knuckle Pin: used in all AAR coupler types

C2 Retainer Pin: used in all AAR couplers with inverted knuckle pins

E6A Top Locklift Assembly: used in all top operating couplers

Type F Couplers and parts are governed by the following AAR Specifications and Interchange Rules:

M-118 Knuckle Pins & Shank Connecting Pins

M-201 General for Steel Castings

S-172 Inspection & Maintenance on Cars

M-211 Purchase & Acceptance

M-212 Secondhand & Reconditioned

Rule 18 Type F Couplers & Parts

Rule 20 Yokes for Type F and E/F Couplers

Rule 88 Couplers & Parts Required for Car Acceptance

Rule 90 Couplers & Parts Prohibited in Interchange

Type F couplers require the use of a flexible coupler carrier due to the Interlocking features of the head end. Vertical and horizontal coupler displacement is provided for in conjunction with the shank connecting pin.