Sgt Foster, who had been slashed in the neck and arms, was able to stem his colleague’s bleeding from the neck with his bare hands before medical support arrived.
Sgt Ansell suffered two open wounds to his neck and further wounds to his arms and body.
Ch Supt Colette Rose, from GMP, said: “The officers attended, on the face of it, a straightforward vehicle stop to assist colleagues.
“Without warning this turned from something quite innocent into a serious life-threatening situation,” she added.
The trio received a nomination at the national Police Bravery Awards on Thursday.
“The heroic actions of these officers prevented this incident from developing any further, and very quickly the suspect was apprehended, preventing any members of the public being caught up or injured,” Ch Supt Rose said.
“They were professional, brave and are a real credit to the organisation. We are all exceptionally proud.”
