Volvo F86 trucks go automatic
Page 23
If you've noticed an error in this article please click here to report it so we can fix it.
An automatic gearbox option has been added to the range of Volvo F86 trucks in the UK. Two Allison units will be available, the MT 640 fourspeed unit with converter lockup in the top two gears and a five-speed version, the MT 650.
In the Allison type numbering system, MT stands for medium truck while the digits "4" and "5" refer to the number of speeds, The 650 is five-speed version, the MT 650. with the addition of an extra deep ratio gear. The MT 640 which in the F86 is suitable for use at a gross weight of 16 tons, has a single stage three element multiphase torque converter and the constant mesh spur type planetary gears give ratios of 3.58, 2.09, 1.39 and 1.00 to 1 forward with a reverse gear of 5.67 to 1 The five-speed MT 650 which is suitable for gross weight of up to 32 tons has ratios of 8.04, 3.58, 2.09, 1.39 and 1.00 to 1 with a reverse of 5.67. The lock-up applies in fourth and fifth gears. Using the 32 ton F86 as an example this lock-up engages at around 40 km/H (25 mph). Both automatics are available immediately as a factory-fitted option on all the 86 range including the Scottish assembled eightwheeler.
No alterations to the engine specification have been necessary and the few chassis modifications include a different cross-member at the rear of the gearbox. To cope with the high oil temperatures sometimes encountered with torque converters an oil cooler is specified which is mounted immediately behind the standard water radiator.
Both Allison variants have built-in inhibitors which prevent engine overspeeding if the wrong gear is selected inadvertently.
As with most things in life you get what you pay for and in the case of the Allison, the claimed advantages of extended transmission life and less driver fatigue cost £1,578 extra for the MT 650. In com parison with the standard clutch/eight-speed gearbox F86 layout the automatic transmission version saves 50kg (1101b) in weight.