what are they?

so i was looking at some of the rides wheels and noticed on mine ride and gemini that there are no bottom wheels but some flat piece in its place. anyone know what it is, or its porpose if it has one? I couldnt really get a good look.

It would be an up-stop. It's what keeps the train from leaving the track when it goes over the crest of a hill. Most newer coasters use wheels for the up-stop which smooths out the ride.

well i figured that but wouldnt they replace it with a wheel? i just figured that it would make it much smoother and to me it kinda doesnt make sense to have a flat piece would slow it down or something... i dont know

Up-stop pads were found mainly on Arrow Dynamics Mine Train coasters. Simple pads work fine instead of wheels on a mine train because most such coasters have very little negative g-forces and do not go very fast. On other coasters with more negative g's and especially ones with inversions, wheels are necessary, ranging from the tiny ones under Magnum to ones that are the same size as the road wheel like on X-Flight (err...Firehawk), depending on the amount of load that will be placed on them.

The pads never touch the track except in extreme circumstances, so they really don't slow it down. I don't know how much wheels would really "make it smoother" on a slow coaster like CMRR. I think the reason for them is to be simpler and less maintenance.
*** Edited 5/13/2007 5:55:23 AM UTC by MillenniumMadMan***

Speaking of the Mine Ride, the load time on that thing is horrendous. Can't they redesign the lap bars to get that thing loaded a little faster and make it so the guests of marginally exceptional size can ride it? It seemed like there was someone on every other train that held it up and eventually got booted because the lap bar wouldn't lock with them in the train.

That or put the extra Gemini Trains on them. Not only would that get rid of the manual lap bar release but also the horendous one size fits all lap bar.

UP-stops used to be on Magnum. When the train did the bunny hills at night you would see sparks flying from the bottom of the train, Speaking of mine ride that line was crazy slow yesterday *** Edited 5/13/2007 1:07:55 PM UTC by Warriors20***

When were the up-stops replaced with wheels?

Well they had only upstops on Magnum at first. I would assume around then. ;)