The overlapping of the spindle drive belts and carriage-drive pulleys makes for a compact installation - but means poor access to the nut which must be undone to change the tumble reverse setting.

Motor pulley, top left, drives to a countershaft idle pulley, centre.
The nut between the vertical runs of the Poly-V belt is slackened to allow the tumble reverse lever to be moved.

Tumble reverse gears

The drive belt is fitted with an effective tensioning device.