SU46 (new symbol[2] 5 630) is the name for a diesel universal purpose locomotive working for Polish PKP.

Both of them has similar shape, but SP47 is a bit longer because of its 2116SSF diesel engine.

SU46 uses a similar diesel engine as SP/SU45, but traction motors are totally different (this was enforced by usage of 3 kV electrical heating).

Order of this locomotive was connected with increasing in 1970s demand on freight and passenger services on non-electrified railway lines.

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