liveried X31 at
Grovedale in April 2007 liveried X41 at
Seymour in November 2007 In preparation for the opening of the
standard gauge line between
Melbourne and
Albury, the
Victorian Railways had purchased a further eight
S class locomotives, with the last of these entering service in 1961. But from that date traffic had increased, with a 20% increase in train miles being run by the end of the financial year by the middle of 1965, so the fleet was being stretched beyond reasonable capabilities. Standard gauge trains at the time were typically rostered for a single S class locomotive, which could deliver approximately 1,800 hp. When one wasn't available, two
T class locomotives (each delivering approximately 950 hp) could be and were used in lieu. This strategy could not, however, be a long-term solution as the T class had been designed for branch-line work and were restricted to 60 mph (96.6 km/h) rather than the 70 mph (112.6 km/h) top-speed of the S class, and the two T class units weighed roughly 24 tonnes (26.5 short tons) more than the single S unit - both major detriments to efficiency. On 23 July 1965, the Chief Mechanical Engineer, Mr Galletly, wrote that there was a need for an additional six 1,800 hp engines, which would allow the T class to be shifted back to their originally-intended duties. The plan at the time was to allocate two of the new engines to Standard Gauge operations, and the other four to Broad Gauge. All six units entered service by the end of 1966. In keeping with the original plan, four of the six were to be converted to broad gauge operation on a rotating basis. Locomotive X31, however, was continually affected by a manufacturing issue with its pneumatically-operated
Automatic Staff Exchanging equipment (which was of a new design) and so was excluded from the conversion rotation until the problem was finally resolved in the mid-1980s at
Newport Workshops - though by this time the use of automatic-exchange equipment in Victoria was rapidly declining. Otherwise, they hauled passenger and freight services throughout
Victoria. On the broad gauge, they operated with the ten broad gauge S Class locomotives, with typical assignments being freight service to
Adelaide, and associated passenger workings like
The Overland and
The Vinelander. However, it was rare for them to venture out to
Gippsland until the late 1970s, and the
Bendigo line was near-exclusively run with
B class locomotives for sake of operational simplicity. X33 was involved in a very serious head-on collision near
Broadford loop only a few months after delivery, on 5 January 1967. It returned to
Sydney for rebuilding by Clyde Engineering. However, X35 suffered much further when it fell off a bridge near
Glenorchy in 1971, following a high-speed crash with a loaded gravel truck. The frame was permanently warped, making it "almost impossible" to properly align the engine and generator units. Not much later it was involved in a side-swipe that gouged a side of the body.
Second Series - X37 to X44 Only a few years after the delivery of X36, a further traffic increase meant additional engines were needed. Clyde Engineering was the only company to submit a tender for the contract (63420) by the closing date of 30 April 1969. On 14 August 2017 Seymour Railway Heritage Centre acquired class leader X31.
Third Series - X45 to X54 A third tender closed on 20 February 1974, for an additional eight or ten locomotives, this time rated for 2,200 hp. The specifications were similar to the as-delivered X37-X44, but with upgraded braking equipment. The reasoning for the order was that, as well as traffic increases (now up to 13.5 million train miles per year), the earlier diesel-electric locomotives were coming due for major overhauls, with no spare motive power to fill the gaps in the rosters (with all steam long-since gone). Two offers were received for contract 64002 - one from
Comeng, offering the standard
ALCO locomotive constructed in with the engine block imported from the US, and Clyde Engineering offered more-or-less a repeat of the previous order for X locomotives, but this time constructed at the then-under-construction
Rosewater, South Australia plant. The offers were designed for an order of either eight or ten locomotives. Aside from the standard purchase order, the tendering companies were requested to offer alternative payment plans, including the rather novel option of leasing the locomotives for 25 years from the manufacturer, rather than outright purchase. This and other options ended up being more expensive than the traditional model (with payments during construction). ALCO's offer totalled about $3.75 million against Clyde's $3.95 million, but this offer was rejected on grounds of much higher maintenance and running costs (based on NSW and SA experiences with ALCO engines), expecting between double and triple the cost per locomotive mile, as well as the need to purchase a separate set of spares for a new ALCO fleet at around $400,000. The final agreement with Clyde was made out at a little under $4 million for ten locomotives, plus another $50,000 for spare parts. During the contract negotiation stage, the VR was pushed by the AFULE to develop a new locomotive cab design intended only for single-end running; attempts to fit the previous X order with bidirectional running proved to be failures on account of driver discomfort. The new cab design allowed only for short-end-leading operation on the mainline, and to improve visibility the short-end nose was cut down to an angled profile similar to the last orders of the T class locomotive. Additionally, the engines were fitted with the upgraded AR10 alternator. The ten new engines were delivered through 1975 on the broad gauge via the
Main Western line. When the first, X45, arrived in Melbourne, it was named
Edgar H Brownbill. This series of engines were normally used on the interstate runs, where multiple engines were required so back-to-back formations overcame the single-end handicaps. In addition, about half the class spent extended periods on standard gauge, and they were the first Victorian Railways class of engine allowed to run in revenue service from Albury to
Sydney from December 1982. ==Modifications to the class==