The 11D-513 engine "straddles" the RD-120 engine on the Zenit second stage and provides stage thrust vector control (TVC).   The engine consists of four separate combustion chambers, a single turbopump assembly and a single preburner assembly.  The engine uses a staged combustion operating cycle with a LOX rich preburner to drive the turbine and turbine exhaust, delivering all of the oxidizer to the main chambers.  All four thrust chamber operated concurrently and are gimbaled.

In the Zenit flight sequence, the 11D-513 is ignited prior to first stage MECO.  Upon first stage MECO, the 11D-513 provides the separation force and propellant settling prior to RD-120 ignition.  Throughout the RD-120 burn the 11D-513 performs second stage TVC.  After RD-120 cut-off, the 11D-513 continues to burn to achieve the proper orbital conditions.  In the two stage mission, the 11D-513 can burn for up to 700 additional seconds to place satellites into higher altitude circular LEO orbits.