Approximately at mid 1970's, exploiting the characteristic of epicyclic rotation given at output, the algebraic sum of two speeds at input, Tandler produced the first mechanical speed modulation precision gearbox. The function of a Tandler planetary speed modulation gearbox is that of producing a temporary negative or positive increase to a basic speed.

Nowadays Tandler produces three series of the so-called second generation speed modulation gearboxes and precisely:

• PE Series, a simple gearbox with increasing or reducing ratio i=3;
  
  
• PD Series, a dual phasing gearbox with ratio i=1;
  
  
• SP Series, a combination phasing gearbox with angular transmission, with inverter or clutch/knock-off device with various reducing and increasing ratios.

Type: PE2
Torque: up to 2.200 Nm
Ratios: from 3:1 up to 1:3
Input speed:
on shaft d1= n1= 3.000 min -1
Angular backlash:
standard <6', reduced <3'

Type: PD2
Torque : up to 6.200 Nm
Ratio: 1:1
Input speed:
n1=1.000 min -1
Angular backlash:
standard <6', reduced <3'

Type: SP2
Torque: up to 2.500 Nm
Ratios: from 1:1 up to 4 ,5:1
Input speed:
on shaft d2= n1=3.000 min -1
Angular backlash:
standard <6', reduced <3'