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Allison Transmission has announced the addition of the six-speed automatic T375 and retarder derivative T375R to its Torqmatic range.

These models are said to be ideal for bus and coach applications up to 360bhp and 1,450Nm torque.

The T375 and T375R will complement the current offerings of Allison’s mid-range fully automatic transmissions, assuring coverage in this segment for the Euro 5 engines.

In addition, the transmission features key fuel-saving technology that is being rolled out across the Allison range.

The T375 and T375R also feature Allison fourth-generation controls.

These controls are said to allow full integration with CAN-based vehicle architectures offering OEMs better powertrain control strategies.

Drivetrain performance is enhanced thanks to the latest versions of closed-loop adaptive logic for shift quality; auto neutral, RELS, eco calibration and load-based shifting scheduling (LBSS) technology for fuel efficiency.

The eco-calibration package ensures the engine operates within a narrow operating speed band while preventing shift cycling.

LBSS technology automatically selects between pre-determined shift schedules, factoring in topography and vehicle load, enabling maximum fuel economy and maintaining vehicle performance.

For shift energy management (SEM)-capable engines, as of 2010, LBSS will be enhanced with super economy shift schedule (SESS) that upshifts the transmission to higher gear at cruise, ensuring the minimum traction effort requirements.

Opportunity to make an upshift in steady-state is greater with SESS, and average engine speed operation is reduced.

Furthermore, vehicle acceleration control (VAC) will be available for customers that require bus acceleration limitation via torque management.

On-road test results demonstrate that the combination of Allison’s features can deliver up to 14 per cent reduction in fuel consumption.

The T375 and T375R models incorporate all the key features from the bus-specific Torqmatic range.

Allison’s Polak gear scheme provides six speeds with the same number of planetary gear-sets as other four-speed transmissions and ensures durability and power-transmission efficiency.

The precision helical cut gears reduce noise inside and outside the bus.

In line with the trend for engines to deliver more power, the cooling system now includes an enhanced 17-plate integral cooler and optional integral sump cooler.

To assure optimum cooling during retarder operation, the integral sump cooler core has two compartments: one compartment for the retarder oil and one compartment for sump oil.

This provides an additional circuit for oil flow during retarder operation, resulting in lower transmission sump temperatures therefore less oil degradation and improved product life.

As part of Allison Transmission’s continuous product improvement initiative, all Allison Torqmatic transmissions are now available with prognostics that determine health of the transmission, and when a specific maintenance function is required.

Allison Prognostics also eliminates unnecessary fluid and filters changes, significantly reducing oil usage and avoiding unnecessary changes.

Allison customers for the T375 and T375R models will also have access to Allison’s optional extended transmission coverage package, providing up to five years’ of coverage.

Allison Transmission

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