It was operating at the dig face pit floor when the operator saw smoke coming from the engine bay area.
The machine was shut down and the onboard fire suppression was manually activated.
The NSW Resources Regulator said the operator used a hand-held fire extinguisher to extinguish the remaining flames.
"The Resources Regulator has developed and issued a discussion paper that considers strategies to reduce the incidence of fires on mobile plant in NSW mines," it said.
"A review of data has identified a concerning increase of reports of fires on mobile plant in New South Wales.
"The reported fires have generally been caused by either the escape of fluids ignited by the hot surface of an engine, or electrical wiring faults."
