Locomotive Descriptions and Phases - ALCO/MLW C-424

These phases are consistent with commonly used C-424 phases, with Phase 3 split into three sub-phases.

Phases 2 through 3c are concurrent with Phases 1 through 2c for the ALCO C-425.

Phases

Phase	1	2	3a	3b	3c
Rear numberboards	Extend beyond carbody	Notched into carbody
Air intake near radiator	Two horizontal openings	Single vertical opening
Battery boxes	Fore and aft of the cab		Under left rear walkway
Side sill	Oblong openings		No oblong openings
Air reservoirs	One on each side		Both on right side
Front air intake	Small square grid, fastened with tabs			Wire mesh on top of large square grid, fastened with rectangular frame
2 Hood doors below exhaust stack	Half-height				Full-height
Phase	1	2	3a	3b	3c

Other details

CP C-424

MLW C-424's used by CP received several exterior modifications during their time in service:

Pilots, ends and underframe:
- Rear open pilot replaced by full pilot plate with rock deflector, as on front
- Both pilots supported by angled pipe, with existing front pilot support plates (behind steps) removed
- Fuel tank drain pipe moved from left to right side
- Battery box housing (under left rear walkway) redesigned with two large hinged panels and larger, flush face plate; 4th handrail stanchion from the rear moved rearward to accommodate battery box panel
- Pilot drop steps added, with chain replacing center solid handrail section and triangular grabirons extending over the drop step
- Front ditch lights added
Cab and short hood
- Headlight moved from cab to short hood on CP 4200-4209 (shortly after delivery)
- Flush inside-hinged doors replaced by outside-hinded, surface-mounted doors; cab handrails angled and moved to cab side to clear doors (some units retained original doors)
- Horn moved from cab roof to long hood; Airchime M3H replaced by Airchime K3L (some units retained horn on cab)
- Louvered vent on right front cab face covered with boxed housing
- Flat sand hatch replaced with taller rectangular hatch
- Bolted rectangular panel added on bottom right side of short hood
Long hood
- Central door handles replaced with top and bottom latches
- Central air intake replaced with 4 square surface-mounted air filters
- Hinged door and intake near radiators replaced with larger, louvered hinged door
- Rear single headlight replaced by dual headlights
- Lighted rear numberboard added; 4th grabiron lowered to accommodate numberboard
- Top-hinged rear sand hatch changed to side-hinged and latched

Additionally, several CP C-424's received alternators from retired M-630 units late in their service careers. These units were CP 4202-4206, 4210-4211, 4213-4215, 4220, 4223, 4228, 4234 and 4244 (possibly others in the mid-1990s). Externally, this modification resulted in the addition of a third air reservoir under the left walkway (for air start) and an additional curved housing above the central air intake. The piping normally located under the left walkway was shortened to make room for the air reservoir. The exact location of the shortened piping and air reservoir straps varied between units.

Dimensions

In May 2013, I made a trip to Exporail and took ground-level measurements of many of the locomotives there. The first drawings to benefit from these measurements were MLW C-424 variations.

Notes:

Several dimensions in the drawing were based on hood measurements I had taken from MLW M-636 #4723; some of these dimensions are illustrated.
Most dimensions also apply to other ALCO/MLW C-424 and C-425 units.
Most hood and handrail dimensions are the same on both sides.
The corner steps extend beyond the pilot face by 3", a distinct feature of MLW Century units and M-liners.
Some dimensions varied slightly between the two units at Exporail (C-424 #4237 and C-424 control cab #1100). As #1100 was a wreck rebuild, I prioritized dimensions from #4237.
The 4th handrail stanchion from the rear was moved rearward from the as-built position due to modified battery box hatches.