How does a machinery sale finish via timer?

Simultaneous (SIM) auctions conclude via a timer system. 

Once the timer is visible at the top of the auction  it controls the auction finishing – dependent on the amount of bidding activity. The timer will count down towards zero, from the nominated time (e.g. 60 seconds), and if no bids are placed, the auction will close.

Every time a bid is placed, on any lot in that auction, the timer will restart and begin to count down again. The auction closes together, meaning all lots remain available until the sale finishes.

If you are bidding in a sale and holding a lot, it will remain green and then turn red if you are outbid. Once outbid, you have the time left shown on the timer to decide if you will place another bid before the auction could close.