Zeroshift is a type of automotive transmission which allows for changing gear without interruption to torque the driving wheels. The Zeroshift principle was invented by Bill Martin, the company Zeroshift Ltd is based in Milton Keynes England.

The Zeroshift gear system is claimed to offer superior performance to a manual transmission as a manual transmission must disengage the engine from the driving wheels to prevent drivetrain wear/damage. An automatic transmission can waste power due to its torque converter if unlocked and usually provides inferior performance compared to a manual.

Currently the Zeroshift transmission is under development with licensing agreements under negotiation. The Zeroshift principle has been demonstrated on a number of the company’s development vehicles. It is expected that if brought to production the Zeroshift transmission may be a replacement for current Semi-automatic transmission.

Method of Operation

The Zeroshift transmission is mechanically similar to a manual transmission with all parts other than the synchro's being the same. The Zeroshift gearbox is operated by "bullets" which engage and disengage the gears. Each set of gears has two bullets: a drive bullet and an overdrive bullet.

Change Sequence

# Bullets engage 1st gear
# Bullets requested to engage 2nd gear, only the overdrive bullet is free to move to engage 2nd gear.
# 2nd bullet engages dog on 2nd gear cog in position, 1st gear bullet is held engaging drive in 1st gear under load due to retention angle on the 1st gear dog
# 2nd gear picks up drive.
# 2nd gear overdrives first gear.
# 1st gear bullet disengages dog and moves to 2nd gear

A problem with the system is that when the transmission instantly shifts between 1st and 2nd gear, the engine, flywheel, and clutch will be spinning at a higher speed than the drive shaft, resulting in a large amount of inertia that must be relieved abruptly across the drive train.

One solution that Zeroshift is currently investigating is to automatically slip the clutch as the gear is changed, in order to stop engine torque transmission and to compensate for the extra inertia by 'dumping' it into the drivetrain. Currently the Zeroshift system is envisaged as a paddle-operated sequential manual transmission. However it could be implemented as a manual stick-controlled transmission where the clutch is used for manual control in low-speed manoeuvres but gearshifts are made without the clutch.

External links

* [] Zeroshift Ltd Homepage
* [ F1 Racing article Oct 2007]
* [ Sport Compact Car article Jan 2006]
* [ Racecar Engineering article Jun 2005]
* [ Racecar Engineering article Feb 2004]

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