A Cash Ladder, along with Nudge, Gamble Feature, Hold Feature & Bonus Trail must be present present for a fruit machine to be considered a fruit machine include.
There are other Fruit Machine Features but the ones listed above must be present for a fruit machine to be classed as a fruit machine and instead of just being a regular slot machine.
There are a couple of ways a cash ladder can work on a fruit machine. The first is for it to flash up and down and the player has to hit stop when it is as near to the top as possible to win the biggest possible prize amount.
The other way a cash ladder might work is to light up one block at a time as the player accumulates points, so that in effect the jackpot that the player can win on the cash ladder is rising all the time (until it is either reset, possibly by some bad luck on the bonus trail or is won). Also as the maximum jackpot is governed by law, the other reason the cash ladder would stop rising would be once the maximum payout allowed by law has been reached.
This Fruit Machine feature gives the player a chance to win one of an array of cash prizes by having the player hit the stop button when he or she feels that the light will land on a high number on the ladder, which acts as a multiplier of your win. Another way this works is to earn your way up the ladder by getting certain symbols during the Bonus Trail and choosing whether to take your winnings or continue to try to climb further up the ladder.