I think originally the comb front didnt have a sickle, but Id say at least from the 1950's on, and quite likely earlier, they did.

They were made to accomodate very light yielding standing cereals ( meaning say...10 bpa), harvested often in 100 plus F temp  and single digit RH % conditions where  shatter loss,  particularly in barley, was a problem.

They choked very easily with  any sort of brassica weeds, and you'd often spend as much time going backwards to try and clear it, as going forwards harvesting.

 Ground speeds in those days were very slow. Now we run our American or European combines at 10 mph, and you are under and beyond the shattering head before it drops to the ground.

These were still made at least well into the 80's, but I dont believe there are any Australian made harvesters any more, that i can think of.

Personally, i dont miss them, and I had  enough personal experience to hate them.  But in their place and in their time, they served a purpose.

They limited the amount of straw input which  on a  walker machine can be an issue  because straw pulverises in our conditions, and makes seperation very difficult.  Rotaries went a  long way to solving that issue.