Tutorials/Minecarts

This tutorial covers basic minecart stations and systems and is designed for those without significant redstone knowledge and only minor experience with minecarts and rails. This tutorial doesn't touch on furnace or  storage minecart. Images below do not always show a space saving design, but rather one that makes all components immediately visible.

Minecarts
The following are the most important properties of minecarts.
 * Minecarts move at 8 m/s at top speed.
 * Minecarts move further with an entity (mob or player) in them than empty.
 * Powered rails, slopes, and pushing provide momentum.
 * Minecarts will slow down and stop if they aren't properly boosted.

Rails
Rail: Allows carts to move over the block. These are the only type of rail that can create a curve in the track. A track can either curve or go up a slope, not both at the same time.

Detector Rail: Whenever a cart moves over this, the rail will create a redstone signal. Otherwise, it functions like a regular straight track.

Powered Rail: When powered, it increases the speed of a moving minecart up to a max of 8m/s. If a minecart is placed on a powered rail, the powered rail will not add momentum since there is no preferred direction. Since 1.3 a minecart can be given a slight nudge from the rider. When accompanied by a solid block on one end (like the launcher below), a minecart is given the preference to move away from the block. When unpowered, this rail will stop a moving minecart.

Activator Rail: When powered, TNT Minecarts going over it will be set off, while a Minecart with Hopper will be disactivated.

Launcher
Launchers, stations or exits all refer to a point in the system where a rider can safely enter or exit a minecart. They generally use a button to launch the cart.

This first design uses a button, a few powered rails, a bit of redstone wire, and a redstone torch. The button powers the powered rail which launches the cart away from the solid block behind it. In this style of launcher, it is important for an incoming minecart to make it all the way up to the back block so it can easily be launched again.

This second design is essentially the same as the first. A dispenser replaces the solid block behind the last powered rail. The dispenser will launch the minecart just like the solid block, but creates a convenient place to store extra minecarts. To activate, use the button behind the dispenser and a minecart will pop onto the rail and be ready for use.

Also see: Tutorials/Minecart_start_booster

Rider Detection
Players will tend to want to detect whether a cart has a player in it or not as empty carts will clog a rail system. This is referred to as rider detection.

A trip wire based design is quick to set up and will reliably detect a player. However, it won't detect some non-player mobs, specifically 'short' mobs (wolves, spiders, pigs, etc).

To build, a trip wire is attached to hooks one block above the track. Two blocks further is a junction which is set by default to turn empty carts back to the station. An empty minecart will not trigger the trip wire and be sent back, while an occupied minecart will send a short pulse to the junction and continue along the rest of the track. Depending on orientation, the signal may need to be inverted with a redstone torch. Although the torch will add delay, it is minor and shouldn't affect the results. This design assumes the minecart is moving at top speed. If your minecart is moving slower than that, you can either add delay to the wire using repeaters or increase the speed of the minecart with a booster just before the trip wire.

Another method to check for a rider is to take advantage of the change in speed of the cart, as an empty cart slows down more quickly. In this design, a minecart will create a pulse when it passes the detector rail. If the minecart is empty, it will get to the turn just as the signal does and be sent back. If the minecart has a rider, it will get to the turn before the signal and be able to continue on. This design requires the track to be set by default to let the cart through.

Empty Carts
When an empty cart is detected, generally it's a good idea to send it into an overflow pile. An overflow pile is a drop of two or more blocks with a rail at the bottom. When carts are boosted into the hole, they will snap to the track, regardless of how many carts are already on the track. This pile should be placed where the carts can be collected, either close to a station or in a maintenance area. It is important to boost carts to full speed just before they are dropped to ensure they don't become stuck on the end of the track and eventually back up the system.

Another variant of this method is to replace the rail at the bottom with a cactus, thus destroying minecarts that fall in.

Boosters
Boosters are a method used to prevent carts from slowing to a stop on a track. Because carts will eventually slow to a halt on level track, and very quickly turn around on regular rail track whilst uphill-bound, boosters are a method of assuring one's cart keeps moving. Boosters accelerate carts to a terminal velocity of 8 m/s, as they use powered rails, and help effectively counter the forces of friction and gravity on the acceleration of the cart. Boosters are simply a single powered segment of powered rail, powered through detector rails, redstone torches or levers next to them. Refer to the diagrams to the right. Players generally keep the distance between boosters uniform, although these distances vary by player. One common, and according to many the most efficient, distribution of powered rails is to place powered rail every 38 blocks on level ground. An easy way to place a lot of track using this count without needing to keep track of each rail is by dividing the rails into stacks of 37, as shown on the right. Approximately 1 out of every 3 rails will need to be powered to travel uphill due to gravity.

Junction
Stations often have one line leading to one destination. Multiple destinations require multiple lines. A junction is a fork in the track where the rider can select which destination he wishes to visit.

This design uses a lever to switch the track and the powered rail will become powered after a preset delay. The detector rail starts the delay. In this design, the lever will always point towards the selected destination regardless of direction.

A junction that has multiple destinations can be setup by expanding the junctions. In the design to the right, the rider is given much more time to select his destination than a two-way junction. He can select any destination by first selecting left or right, then forward or backward. This design doesn't scale well but can be used in sequence to create any number of destinations.

Multiple Destination Selector
There are many, many styles of minecart destination selectors. Most are modular, meaning they can be extended to include more destinations. An RS-NOR latch array is often used to select a destination as these latches have a designated reset line (as opposed to a t-flip flop which only has one input).

This design was selected for it's simplicity and for it's ability to be expanded with relative ease. One of the buttons on the selection panel is a designated reset line since additional input doesn't clear the previous selection; that is to say, a player can select more than one destination with this design (although a launched minecart will take the left-most of the selected destinations).

Video Tutorial by CNB

The following design is heavily influenced by the previous but uses a different RS-NOR latch design involving pistons. It has a reset integrated in the selection such that a new input will clear a previous one. By removing the designated reset line of the previous version, it allows for an additional station in a similar amount of space.

Video Tutorial by redminecraftstonetut

Troubleshooting
When a track system isn't working properly, it can be difficult to fix for someone unfamiliar with redstone and rails. Common solutions include: Searching on the minecraft forums can help. If you need to create a new post, be sure to include the direction you're working (the F number), as directionality can be a factor in the design.
 * Changing the delay of circuit by adding a repeater or moving a detector rail to trigger earlier.
 * Changing the speed of the minecart by adding powered rails or moving the current ones further away.
 * Checking that powered rails are powered properly.
 * Turn the design around, as direction can affect how it works. Generally this isn't the issue, but it's good to rule it out.