Train-brakes were controlled by the road engineer in the lead unit, SP 8278. Dynamic and independent brakes were controlled separately by each engineer in their respective units, helper or road locomotive.
Based on statements by the head-end and helper engineers, the dynamic brakes of Units SP 8278 and SP 7443 were known to be functioning. Unit SP 7551 was dead-in-consist with no dynamic brakes or power. The dynamic brakes of unit SP 8317 were tagged and out of service, but the unit pulled in the power mode and had pneumatic brakes. The head-end engineer stated that he believed "the third unit (SP 7549) had fairly good, I think they were good dynamics." The event recorder printout for SP 7549 did not show any amperage in the dynamic mode after the train departed Oban where the helper units were added. The fourth unit, SP 9340, was reported by the head-end engineer to load in and out of dynamics intermittently.
The automatic and independent brake valves from units SP 8278 and SP 7443 were bench tested on May 15, at the SP diesel shop in Los Angeles in accordance with the requirements of the manufacturers and the Association of American Railroads. All valves performed within design specifications.
The controlling locomotive units at the head end and rear end of the train, SP 8278 and SP 7443 respectively, were equipped with multi-channel radios that broadcast on 30 watts of power at 72 volts. The road channel was 161.550 MHz. Both radios Were bench tested on May 14 and 15, at the SP radio facility at Colton Yard. Both radios functioned according to design and Federal specifications (49 CFR Part 90). On May 12, an on-scene functional test of the radio from SP 7443 transmitting to the Colton roundhouse was performed; communication was loud and clear.
The first three head-end locomotive units of Extra 7551 were equipped with Pulse 8 event recorders; the fourth head-end unit and the helper units were not equipped with any event or speed recorder. None of the units were required to be equipped. According to SP’s general road foreman, all new locomotives being purchased are equipped with event recorders, and event recorders are being installed on existing locomotives during a major overhaul. The helper units had not recently been through a major overhaul maintenance program. The Pulse 8 event recorder cartridges record speed, time, distance, direction, amperage, braking, throttle position, and independent brake application. All three event recorder cartridges were recovered and taken by Safety Board personnel to its headquarters in Washington, D.C., for restoration (the cartridge from unit SP 8278 was heavily damaged) and printout . (See "Tests and Research," "Event Recorders.")
Hopper Cars.—Of the 69 open-top hopper cars in the consist of Extra 7551 East, 38 cars were owned by the SP. These cars were 48 feet 9 inches in length, had a light weight of 60,300 lbs, a maximum lading capacity of 202,700 lbs for a maximum weight per car of 263,000 lbs. The remaining 31 cars were owned by the Denver & Rio Grande Western Railroad (DRGW). These cars were 51 feet 8 inches in length, had a light weiaht of 63,500 lbs, a maximum lading capacity of 199,500 lbs for a maximu weight pr car of 263,000 lbs. The total light weight of the 69 cars was 2,130 tons.