Early rail motor transmissions were of the manual type. The conversion of a derelict Moreland lorry in 1919 into Rail Motor No.1 used the standard motor lorry type 3-speed manual transmission (gearbox) driving by a propeller or cardan shaft through a normal differential on the single fixed drive axle. Rail Motor No.1 was single ended and had to be turned when reaching the terminus. In 1921, Rail Motor No.2, was constructed with an Eveleigh Workshops built 3-speed manual transmission. The drive train was by a cardan shaft to a worm driven final drives on one bogie with both axles driven. Rail Motor No.2 was double-ended and reversing was achieved by reversing the direction of the engine rotation using two sets of pneumatically actuated camshafts, one for either direction.
The 42-Foot Rail Motors followed on from the earlier designs, initially with a Thornycroft 4-speed manual transmission, while later vehicles were fitted with an Eveleigh Workshops designed 4-speed manual transmission. Both variants drove by a cardan shaft to a reversing final drive. The reversing final drive had two crown wheels in constant mesh with the drive pinion and the running direction was selected by a pneumatically actuated sliding dog clutch that engaged into one of the two crown wheels.
The Rail Buses, introduced in 1937 all featured manual transmissions similar to those used on trucks and buses of a comparable size.
The hydraulic torque converter originated as a hydraulic speed transformer to provide speed-reducing gears for marine steam turbines. This was patented in 1905 by Dr Hermann Föttinger and was known as the Föttinger Transformer. The development of helical reduction gearing for steam turbines by Britain’s Charles Parsons made the hydraulic speed transformer redundant, and other applications for the device were investigated. Föttinger designed a transmission for a 1600 hp locomotive in 1926. This transmission employed two torque converters and a fluid coupling operating in sequence. Although the locomotive was never constructed, the design principle was later used in transmissions manufactured by Voith.
During the late 1920s other engineers such as Sweden’s A J R Lysholm and Britain’s Coates interested themselves in the development of the hydraulic torque converter. Lysholm developed the multi-stage torque converter, while Coates designed a torque converter with pivoted guide vanes that automatically adapted themselves to the direction of flow of the transmission fluid. Alf Lysholm (1893-1973) was the Chief Engineer of a Swedish engineering company, Ljungstroms Angturbin AB, and these early torque converters were based on many of his developments. Lysholm made several inventions, including a turbine blade with a thick, rounded inlet edge. This was intended for use in steam turbines but found even wider application in hydraulic torque converters. This new turbine blade was used in hydraulic transmissions for buses, railcars, and locomotives, notably in military vehicles manufactured during World War II. The Lysholm-Smith type torque converter found great acceptance in the USA where it was the subject of further development. These transmissions were generically known as the twin disc type. In 1933, a twin-engine, bogie rail car with hydraulic transmissions began operating for the London Midland and Scottish Railway (LMS) subsidiary in Northern Ireland in 1933. This vehicle used underfloor Leyland engines coupled to Lysholm-Smith hydraulic torque converters. LMS also built an experimental three-car articulated railcar train in 1938, using the same engines and transmissions. It is probable that the engines and transmissions used in these vehicles were the same as those used in NSW Rail Motor No.38 and the later 400 Class.
The fluid coupling uses a transmission fluid as the medium to transmit power from the engine to the drive train. The coupling consists of two sets of facing rotating vanes or blades encased in a sealed housing containing the transmission fluid. One set of vanes, the pump or impeller, is connected to the engine by the input shaft, while the other, called the turbine, is connected to the drive train by the output shaft. There is no physical connection between the impeller and the turbine. Rotation of the impeller imparts torque (or energy in the form of motion) to transmission fluid, which in turn causes the turbine to rotate. In a fluid coupling, the torque delivered to the turbine equals the torque absorbed by the pump. Efficiencies with this form of coupling can reach more than 90%. Excess energy is generated in the form of heat in the transmission fluid and the fluid is passed through a heat exchanger to provide cooling and maintain the viscosity of the fluid.
Like the fluid coupling, the torque converter uses a transmission fluid as the medium to transmit power from the engine to the drive train. The energy in the moving fluid in turn causes a turbine that is attached to the vehicle’s drive train to rotate thus providing the power to move. The principal difference to the fluid coupling is that in addition to the pump (impeller) and turbine, the basic torque converter has a fixed set of vanes known as the reactor that causes the reaction torque (that is, fluid returning from the turbine) to be returned back to the turbine. This torque is in addition to the input torque and amplifies the power being imparted to the turbine. In later models, a freewheeling set of vanes or blades, called a stator, is located between the impeller and the turbine and redirects the moving fluid back onto the turbine in place of the reactor. The faster the engine turns the impeller, the more torque is applied to the fluid, resulting in more power being output to the turbine and then to the drive train. The torque converter provides an infinite range of ratios between the transmission’s input and output speeds. Once the rotational speed of the turbine approaches that of the impeller, the effectiveness of the torque converter diminishes.
The hydraulic torque converter originated as a hydraulic speed transformer to provide speed-reducing gears for marine steam turbines. This was patented in 1905 by Dr Hermann Föttinger and was known as the Föttinger Transformer. The development of helical reduction gearing for steam turbines by Britain’s Charles Parsons made the hydraulic speed transformer redundant, and other applications for the device were investigated. Föttinger designed a transmission for a 1600 hp locomotive in 1926. This transmission employed two torque converters and a fluid coupling operating in sequence. Although the locomotive was never constructed, the design principle was later used in transmissions manufactured by Voith.
During the late 1920s other engineers such as Sweden’s A J R Lysholm and Britain’s Coates interested themselves in the development of the hydraulic torque converter. Lysholm developed the multi-stage torque converter, while Coates designed a torque converter with pivoted guide vanes that automatically adapted themselves to the direction of flow of the transmission fluid. Alf Lysholm (1893-1973) was the Chief Engineer of a Swedish engineering company, Ljungstroms Angturbin AB, and these early torque converters were based on many of his developments. Lysholm made several inventions, including a turbine blade with a thick, rounded inlet edge. This was intended for use in steam turbines but found even wider application in hydraulic torque converters. This new turbine blade was used in hydraulic transmissions for buses, railcars, and locomotives, notably in military vehicles manufactured during World War II. The Lysholm-Smith type torque converter found great acceptance in the USA where it was the subject of further development. These transmissions were generically known as the twin disc type. In 1933, a twin-engine, bogie rail car with hydraulic transmissions began operating for the London Midland and Scottish Railway (LMS) subsidiary in Northern Ireland in 1933. This vehicle used underfloor Leyland engines coupled to Lysholm-Smith hydraulic torque converters. LMS also built an experimental three-car articulated railcar train in 1938, using the same engines and transmissions. It is probable that the engines and transmissions used in these vehicles were the same as those used in NSW Rail Motor No.38 and the later 400 Class.
The fluid coupling uses a transmission fluid as the medium to transmit power from the engine to the drive train. The coupling consists of two sets of facing rotating vanes or blades encased in a sealed housing containing the transmission fluid. One set of vanes, the pump or impeller, is connected to the engine by the input shaft, while the other, called the turbine, is connected to the drive train by the output shaft. There is no physical connection between the impeller and the turbine. Rotation of the impeller imparts torque (or energy in the form of motion) to transmission fluid, which in turn causes the turbine to rotate. In a fluid coupling, the torque delivered to the turbine equals the torque absorbed by the pump. Efficiencies with this form of coupling can reach more than 90%. Excess energy is generated in the form of heat in the transmission fluid and the fluid is passed through a heat exchanger to provide cooling and maintain the viscosity of the fluid.
Like the fluid coupling, the torque converter uses a transmission fluid as the medium to transmit power from the engine to the drive train. The energy in the moving fluid in turn causes a turbine that is attached to the vehicle’s drive train to rotate thus providing the power to move. The principal difference to the fluid coupling is that in addition to the pump (impeller) and turbine, the basic torque converter has a fixed set of vanes known as the reactor that causes the reaction torque (that is, fluid returning from the turbine) to be returned back to the turbine. This torque is in addition to the input torque and amplifies the power being imparted to the turbine. In later models, a freewheeling set of vanes or blades, called a stator, is located between the impeller and the turbine and redirects the moving fluid back onto the turbine in place of the reactor. The faster the engine turns the impeller, the more torque is applied to the fluid, resulting in more power being output to the turbine and then to the drive train. The torque converter provides an infinite range of ratios between the transmission’s input and output speeds. Once the rotational speed of the turbine approaches that of the impeller, the effectiveness of the torque converter diminishes.
In 1949, the branch line 600/700 Class 2-car unit used the more powerful Model 6081 version of the Detroit Diesel 6/71 engine but used the General Motors Allison Torqmatic TCLA 655 type. This transmission had no neutral position and required the engine to be shutdown to change direction. This was not a problem during branch line service, but when they reverted to suburban service towards the end of their lives, air starter motors had to be fitted to the engines to save the drain on the train batteries. The Allison transmission was the first used in NSW to feature automatic lockup, but reversing was still carried out in the final drive. They were multiple unit compatible only within the class and this eventually led to five of the 10 sets being re-engined as 660/760 Class and to make them compatible with the later 620 and 900 Classes. A TCLA 655 transmission was fitted to CPH 2 and CPH 19 for a period, probably for experimental or trial purposes.
The Harland and Wolff engines used in the 100 Class power vans were found to provide insufficient power to haul a full Comet 5-car set and despite attempts to provide additional power from the engines it was decided to replace the power plants with four vertical Detroit Diesel 6/110 series engines. The transmission selected was the Allison Torqmatic TCLA 965 type and was larger version of the Allison 655 type used on the 600 Class. The power van was fitted with four traction engines, in facing pairs, with each driving through the Allison transmission into a common gearbox. The gearbox output shaft drove the reversing final drive by a cardan shaft. Like the Allison TCLA 655, the TCLA 965 transmission also had no neutral position and required the engines to be shutdown to change direction. Again this was not a real problem for the long distance running Comet trains.
Closely paralleling the development of the 600/700 Class was the main line 900 Class or DEB sets of 1951. These air-conditioned units were fitted with two Hercules DFXH-F diesel engines, each coupled to a Torcon torque converter transmission. Little is known about the Torcon transmission, however, contemporary reports in Railway Transportation indicate that the transmission had a torque converter and fluid flywheel arrangement. An electro-pneumatically operated “rocker brake” was provided on the transmission universal joint flange to enable the direction of travel to be reversed. This would seem to indicate that the Torcon transmission was continuously engaged while the engine was running (like the Allison TCLA type) and did not have a neutral position. A Torcon transmission was fitted to CPH 16 between 1949 and 1951, probably for trial purposes. The Hercules/Torcon combination was unsuccessful in revenue service and led to the first set being withdrawn from traffic after only 6 months of operation and work on further cars was suspended. The replacement was the Detroit Diesel 6/110 Model 62802RA engine coupled to an Allison TCLA 965 hydraulic transmission. This transmission was the same as that deployed in the 100 Class power vans and required the engines to be shut down to reverse direction. Later units (from PF 906 and HPF 954) were fitted with the Detroit Diesel 6/110 Model 62808 engine coupled to an Allison RC3 3-position transmission with automatic lockup and this transmission featured an integrated forward and reverse gear train. The direction was engaged by the action of either the forward or reverse clutches. The GM 6/110 engine and Allison transmission proved to be a more reliable combination and construction of the 36 power and trailer cars of the class resumed in 1954 and all were completed by 1960. The RC3 type was the first transmission to feature an integrated reversing mechanism and the reversing final drive of the earlier types was dispensed with and a fixed Spicer Model 8 final drive fitted.
The 620/720 Class 2-car units entered service from 1961 for suburban and outer suburban use. Six of the early sets were fitted with two Rolls-Royce C8SFLH diesel engines coupled to Rolls-Royce DFR 11500 Series Ms.300 transmissions and Rolls-Royce CG.100 reversing gearboxes, while the remainder were fitted with an updated version of the 900 Class equipment of two Detroit Diesel 6/110 engines and Allison RC3 transmissions. The Rolls-Royce transmissions were built under licence from the designers, Twin Disc (USA) and this transmission was of the 3-position type with automatic lockup. The last unit of the Class had Cummins NHHRTO-6-B1 diesel engines coupled to Twin Disc DFFR 10034-1 transmissions and Twin Disc RR303 reversing gearboxes. Like the other transmissions used in the Class, the Twin Disc unit was a 3-position type with automatic lockup. This meant that the Rolls-Royce, GM and Cummins powered units could all work together in multiple. They were also compatible with members of the 900 Class. Fixed Spicer Model 8 final drives were used with all three engine configurations.
In 1961, the five 1100 Class or Budd cars entered service. The four power cars had two Detroit Diesel 110 series model 62806RD engines. This engine was a packaged railcar unit and featured an integrated Allison RC3 transmission but was sold under the Detroit Diesel brand name. The transmission was the same 3-position type used in the 620 and 900 Classes. While they were fitted with common engine and transmission, the 1100 Class could not work in multiple with the 620 and 900 Classes.
The Pay Buses, introduced in 1968, featured a Voith DIWA transmission. The DIWA (DIfferential WAndler) transmission functions on the basis of power separation. The engine power is split into mechanical and hydrodynamic components, which are later re-joined in the output drive. The result of this differentiating power process is a continuous acceleration within a speed range where more conventional gearboxes must be shifted 2 to 3 times. Not only does this reduce the amount of gearshifts by some 50 percent, it also means better fuel consumption in the lower speed ranges thanks to the partly mechanical power transmission as well as a diminished thermal load on engine cooling using the power-split principle.
The relatively unsuccessful 1200 Class or Tulloch cars appeared in 1971. These vehicles were fitted with two Cummins NTA-855-R2 diesels coupled to Voith T113r transmissions. The Voith transmission was a 3-position type with an integrated reversing gear train. The T113r differed from the Rolls-Royce, Allison and Twin Disc types in that the mechanical direct drive component was replaced with a fluid coupling. Starting was achieved by a normal torque converter arrangement while the high-speed component used a fluid coupling that is able to deliver almost equivalent power to the mechanical direct drive arrangements of the earlier transmissions. Despite this difference, the basic operation of the transmission was similar to the other types and could be controlled in the same manner with the added advantage of a very low wear factor. The 1200 Class were electrically compatible with the 1100 Class and could work in multiple with them, but as with the 1100 Class, they were incompatible with the 620 and 900 Classes.
In 1971, 22 Cummins engines and Twin Disc DFFR 10034 transmissions were purchased to upgrade the ten aging 600 Class sets. Around this time a number of the early 620 Class sets were also suffering from overage equipment and some of these new engines and transmissions were diverted to upgrade members of the 620 Class. In the end, only five 600 Class sets were converted to 660 Class between 1971 and 1975. They were fitted with two Cummins NTA-855-R2 engines coupled to Twin Disc DFFR 10034 torque converter transmissions with Twin Disc RR303 reversing gearboxes. This Twin Disc model was also a 3-postion type and as part of this conversion they were made compatible electrically with the 620 and 900 Classes. As a result, the remaining five 600 Class sets did not receive the new equipment and continued on until their withdrawal from service with their original Detroit Diesel 6/71 engines and Allison TCLA 655 transmissions.
In 1978, the first Japanese Niigata transmissions (Model DBRG2115) were fitted to the Cummins engined 620 Class unit MPF 638. The Niigata transmissions were built under licence from Twin Disc Incorporated (USA) and being similar in operation to the other Twin Disc and Allison types in service meant that 638 could work in multiple with the other 620 and 900 Class units. Unlike other transmissions in use, the DBRG2115 unit was not fitted with a “free-wheel” device that prevented the over revving of the engines on long downhill runs. By the early 1980’s the 620 and 900 Class equipment was becoming unreliable and the success of the Niigata transmission trial in MPF 638 led to a program of re-powering 900 Class power cars with Cummins NTA-855-R4 engines and a newer Niigata Model DAFRG2001 transmission (fitted with a “free-wheel” device). Part way through the project, the use of the Niigata transmission was abandoned due to operational problems being experienced and the Voith Model T211r transmission was substituted. The use of The Cummins NTA-855-R4 engine and Voith T211r transmission was later extended to the surviving 620 and 660 Class units.
The Endeavour and Xplorer cars, introduced in 1993, are powered by a single Cummins KTA-19R diesel engine driving a Voith T311r hydrodynamic transmission. The T311r transmission is a 2-speed type and features a torque converter and a fluid coupling. Lockup is automatic and a freewheeling mechanism is provided that drains fluid from the fluid coupling to prevent over speeding of the engine. These cars also featured Voith V15/20 final drives that enable both axles on one bogie to be driven.
The newest rail cars on the system are the Hunter rail cars. All cars are powered by a single Cummins QSK19-R diesel engine driving a Voith T312bre hydrodynamic transmission. The T312bre transmission is a 3-speed type and features a torque converter and two fluid couplings. Lockup is automatic and like the T311r, a freewheeling mechanism prevents over speeding of the engine. Voith SK-485 final drives are fitted to both axles of the driving bogie.
The Voith T113, T311 and T312 type transmissions differed from others used in NSW in that they were driven from the engine by a separate cardan shaft rather than fitting directly onto the rear of the engine block flywheel housing like the Voith T211, Twin Disc, Allison and Niigata types.
The basic rail car final drive is a crown wheel and pinion arrangement with the power being transmitted from the engine and transmission by a cardan shaft to the final drive. In the early rail motors, from the CPH Class through to the early 900 Class, the final drives provided the mechanism for reversing the vehicles direction. These consisted of two crown wheels, one on either side of, and in constant mesh with, the driving pinion. These crown wheels rotated in opposite directions and were free to rotate on the driving axle. The crown wheels were engaged by a sliding dog clutch that was mounted on splines on the driving axle. When the driver engaged the direction control lever it activated a magnet valve and air pressure moved the sliding dog clutch to engage one of the crown wheels and the vehicle direction was selected.
The CPH and 400 Class final drives did not have a neutral position that could be selected from the driver’s control stand. They could, however, be placed in the neutral position (or “centred”) by manually turning a nut on the top of the final drive with a spanner. The 100 and 600 Class final drives could be “centred” by placing the driver’s reverser lever in the centre position. In these two classes the transmission did not have a neutral position and the engines needed to be shutdown in order to select or to change the direction of travel.
In the later types, from the 900 Class onwards, the transmissions were fitted with either a reversing gearbox or had an integrated reverse gear train incorporated into the transmission. The Twin Disc, Niigata and Rolls-Royce transmissions (the latter two being license built Twin Disc designs) had a separate reversing gearbox. The Twin Disc RR303 and Rolls-Royce CG.100 reversing gearboxes were fitted immediately behind the transmission. These reversing gearboxes were similar in operation to the reversing final drives and featured a pneumatically operated sliding dog clutch that engaged one or other of the bevel gears to drive the output shaft for the selected direction.
The XPT Power Cars were, in essence, a Bo-Bo diesel-electric locomotive and used a standard diesel-electric locomotive type electric transmission. These vehicles were fitted with a Brush BA10003A/BAE506A alternator for traction and a Brush BAH601B/BAE502B alternator for auxiliary power for air-conditioning and buffet supplies. Traction motors were Brush TMH68-46 Mk.III.
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