On one trip to England I was intrigued by a machine that had a bunch of different coins sliding back and forth on a ledge.
You would drop in a coin, which seemed to join the others, but now the ledge overflowed and a coin or several would fall down to the winner slot.
I tried to tell people about it but could not say how it was supposed to work, what the premise was.
What is it called and how does it work?
No idea what they’re called.
The basic idea is the possibility that your single coin might be enough to push a huge load over the edge. More likely, of course, is that yours contributes to the growing pile. And as with all forms of gambling which have guaranteed returns for the owner, the odds of winning appear to increase the more you plug into it. (Plus the ever-increasing suspicion that some of the piles have been glued into place by the owners.)
Little to add, except to say that I have some recollection of seeing similar things here in America. I’m thinking that they were within the context of a video arcade, with the coins replaced by tokens. It must’ve been when I was a little kid, though, as the memory is pretty faint.
It’s called the penny falls - coins build up on the ledges and adding new ones at the top dislodges the ones at the front, but in random bursts, so the chance element is in whether the coins are stacked up ready to fall - they often look like they are much more precariously balanced than is in fact the case.
The machine also incorporates a couple of take-off chutes at the side, so anything pushed off the sides goes to the house. There are often higher-value prizes placed on top of the coins, but these hardly ever fall down.
oops - note of clarity - ‘falls’ as in waterfall
Here in Maryland, the coins fall off the edge and a ticket comes out of the machine. Collect about 5000 of them and you can redeem them for a cool 5 cent fluorescent purple Barney eraser 
You see machines like these in Vegas Casinos sometimes. Usually you have to put in Quarters.
Let’s try that again
I think a Barney eraser is all I would get out of it.
So does it take different size coins, and why would you put in one with larger value?
IIRC, they take only a particular coin denomination. They could be set up for quarters or pennies or in the UK, 2p, 10p etc.
Cynic.
Years ago I had a summer holiday job in an amusement arcade which had one of these machines. It wasn’t necessary to glue coins into place because Penny Falls was such a good moneyspinner anyway. From the arcade’s point of view the main problem with the game was the frustration experienced by the player. Many of them couldn’t believe the pile they had ‘aimed’ for hadn’t toppled into the winner’s chute. This sometimes motivated them to bang the machine hard with whatever part of their body seemed suitable for the purpose.
The strategy rarely worked, but customers could occasionally be seen leaving the arcade rubbing their backsides somewhat ruefully.
Also, as I recall, we would tempt players by placing silver coins on the fall area in addition to the pennies.
Not a larger value, but a larger size. Sometimes it just seems like a big ol quarter it gonna knock everything off the edge, but alas nothing.
PS The ones I’ve seen usually only take one size, bigger ones don’t fit, smaller fall through a different slot.
PPS I always called it The Bulldozer game and 'round here you tend to find them at carnivals.
>>nitpick<< They’re called penny cascades not falls.
Yes, this what what had puzzled me. I wondered how the mix of coins got there. That was what puzzled me most, who would have put in the more valuable coins.
The owner, yanno, the guy with the tube of superglue 
I’ve seen them with five pound notes, dolls, shitty prizes and so resting on top of the coins to tempt you to use them too.
The mention of Bulldozer game led me to a few more references, like this one from the Montana Gambling Laws
23-6-104. Amusement games allowed may be made available for public play.
(h) Miscellaneous games.
(i) **ll chute (bulldozer) (penny fall). **
(A) The games in each of the following sentences require the player to insert a coin or token into a chute, aiming the coin or token so that it will fall in front of a continuous sweeper (bulldozer) operating on a playing field containing additional coins, tokens, or merchandise. A coin that is aimed correctly will cause a sweeper (bulldozer) operating on a playing field containing additional coins to push coins into a counting mechanism that will convert the coins into tokens or tickets and dispense them to the player.
(B) There may not be a ledge, tip, or similar obstruction that inhibits the passage of coins, tokens, or merchandise into the counting mechanism, hole, or chute.
Nice nitpick, considering that everyone seems to remember them as penny falls and there’s even a picture showing that name.
I had fun playing with those things when I was in London. Never played them here though, although I’ve seen them.
