Although most railroads did not have a specific name for this wheel arrangement, the C&O called them "Chesapeakes" while the SP called them "Mallet Consolidations".
Norfolk & Western made this design famous by spending many years putting a lot of effort into perfecting the compound design. The N&W ended up with the ultimate stump-puller in their 2-8-8-2s with unsurpassed pulling ability. Fortunately, two of these impressive steam locomotives survive today.
If you were to ignore all of the unsuccessful and experimental locomotives, then look at the overall ratings of the remaining steam locomotives in the above categories, it would become clear that there were many large locomotives. One could argue that the Big Boys were the largest and maybe they were. But the NP Z-5, the DM&IR M-3/4, the C&O H-8, and the N&W Y6b were all examples of the largest of all successful steam locomotives.
Railroad | WP | N&W | GN | NP | SP | DM&IR | B&O | SP | UP | UP | C&O | N&W | PRR | PRR | South African Railways |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Class | M-137 | Y6b | R-2 | Z-5 | AC-9 | M-3/M-4 | EM-1 | AC-10/11/12 | Big Boy (4884-2) | 4664-5 | H-8 - 1645 | A | Q2 | S1 | GL |
Wheel Arrangement | 2-8-8-2 | 2-8-8-2 | 2-8-8-2 | 2-8-8-4 | 2-8-8-4 | 2-8-8-4 | 2-8-8-4 | 4-8-8-2 | 4-8-8-4 | 4-6-6-4 | 2-6-6-6 | 2-6-6-4 | 4-4-6-4 | 6-4-4-6 | 4-8-2+2-8-4 |
Series | 251-260 | 2171-2200 | 2044-2059 | 5001-5011 | 3800-3811 | 220-237 | 7600-7629 | 4205-4294 | 4020-4024 | 3930-3949 | 1645-1659 | 1200-1242 | 6175+ | 6100 | 2350-2357 |
Cyl:Dia x Stroke | 26x32 | 25x32 | 28x32 | 26x32 | 24x32 | 26x32 | 24x32 | 24x32 | 23.75x32 | 21x32 | 22.5x33 | 24x30 | 19.75x28 | 22x26 | 22x26 |
Driver Diameter | 63 | 58 | 63 | 63 | 63.5 | 63 | 64 | 63.5 | 68 | 69 | 67 | 70 | 69 | 84 | 48 |
Boiler Pressure | 235 | 300 | 240 | 250 | 250 | 240 | 235 | 250 | 300 | 280 | 260 | 300 | 300 | 300 | 200 |
Grate Area | 145 | 106.2 | 126 | 182 | 139.5 | 125 | 117.5 | 139 | 150 | 132 | 135 | 122 | 121.7 | 132 | 75 |
Evaporative Heating Surface | 6,811 | 4,915 | 7,869 | 7,673 | 6,918 | 6,782 | 5,298 | 6,470 | 5,755 | 4,642 | 6,795 | 6,639 | 6,725 | 5,661 | 3,396 |
Superheater Heating Surface | 2,152 | 1,478 | 3,515 | 3,219 | 2,831 | 2,770 | 2,118 | 2,616 | 2,043 | 1,741 | 2,922 | 2,703 | 2,930 | 2,085 | 835 |
Weight on Drivers | 552,700 | 548,500 | 544,000 | 558,900 | 531,200 | 560,257 | 485,000 | 531,700 | 545,200 | 404,200 | 504,010 | 432,350 | 393,000 | 281,450 | 324,464 |
Total Engine Weight | 665,100 | 611,520 | 630,750 | 723,400 | 689,900 | 695,040 | 628,700 | 657,900 | 772,250 | 634,500 | 751,830 | 573,000 | 619,100 | 608,170 | |
Maximum Axle Weight | 69,088 | 68,000 | 70,900 | 66,400 | 62,100 | 69,100 | 67,800 | 85,480 | 72,000 | 79,780 | 40,992 | ||||
Tender Weight | 408,250 | 378,600 | 372,780 | 402,000 | 400,700 | 438,000 | 382,000 | 393,300 | 436,500 | 434,500 | 431,710 | 378,600 | 422,000 | 451,840 | |
Total Engine and Tender Weight | 1,073,350 | 990,120 | 1,003,530 | 1,125,400 | 1,090,600 | 1,133,040 | 1,010,700 | 1,051,200 | 1,208,750 | 1,069,000 | 1,183,540 | 951,600 | 1,041,100 | 1,060,010 | 472,864 |
Overall Wheelbase | 108 | 114.87 | 106.02 | 110.08 | 112.99 | 113.49 | 112.5 | 112.17 | 117.58 | 106.67 | 112.92 | 108.27 | 107.62 | 123.76 | 83.58 |
Tractive Effort | 137,174 | 124,644 | 162,475 | 145,930 | 123,364 | 140,093 | 115,056 | 123,364 | 135,375 | 97,352 | 110,211 | 125,897 | 100,816 | 76,403 | 89,137 |
Tractive Effort Booster | 13,900 | 13,400 | 15,000 | ||||||||||||
Maximum Speed | 50 | 63 | 80 | 70 | 60 | 100 | |||||||||
Drawbar Horsepower | 5,600@25 | 6,000@40 | 6,345@41.5 | 7,498@46 | 5,300@43 | 7,200 |
No. | Class | F.M. Whyte | Gauge | Railroad Line | Location | Status | Builder Info | Notes |
---|---|---|---|---|---|---|---|---|
2050 | Y3a | 2-8-8-2 | 4'-8½" | N&W | Illinois Railway Museum, Union, IL | display | ALCO (Richmond) #64070, 1923 | Came to the museum in the late 1970s. |
2-8-8-2 | 14½" | Whiskey River | unknown, Cleveland, OH | stored | From Marshall, WI; being regauged to 16 | |||
2156 | Y6a | 2-8-8-2 | 4'-8½" | N&W | Virginia Museum of Transportation, Roanoke, VA | display | N&W #317, 1942 | On loan from St. Louis MoT for five years |