The KTDU-35 (GRAU Index 11D62) was a Soviet spacecraft propulsion system composed of two liquid rocket engines, the primary, S5.60 (SKD) and the secondary S5.35 (DKD), fed from the same propellant tanks.
Both engines burn UDMH and AK27I in the gas generator cycle.
[3] Within the Soyuz and Progress, the SKD is the primary engine, the DKD is the backup engine for main orbital correction and de-orbit operations.
The engine generate 4.09 kN (920 lbf) (SKD) or 4.03 kN (910 lbf) (DKD) of thrust with a specific impulse of 278 seconds and 270 seconds, respectively.
The spacecraft attitude system (DPO) is responsible for pointing the vehicle in the correct direction and keep it that way during SKD burns.