A robotic lift is a mechanical system in the robot that allows the change of positioning, typically height, of another mechanism or object. Lifts are typically used in conjunction with a claw, intake, or launcher to move, place, reposition or retrieve objects to places the robot would otherwise be unable to reach. Various types of lifts exist and each have their own purpose and capabilities.

The following list features lifts commonly used in VRC. However, some of these designs are also used in other robotics competitions such as VEXIQ and VEXU.

Bar lifts use rotational motion to rotate an arm usually made of c-channel to reach high places. This rotational motion allows objects attached to the lift to rotate at an arc, usually resulting in the attached mechanism to reach out as it gets higher. Of the common lift designs, bar lifts are more versatile due to its simplistic design and the amount of variations developed for this type of lift. However, they are limited by their comparitively low (compared to a reverse bar or scissor) reach though bar lifts can reach higher by stacking more bars above the existing bar.

Common variations of the bar lift include:

• 2 bar
• 4 bar
• 6 bar
• 8 bar
• Chain bar

Advantages

• Simplistic, user friendly design
• Reaches outward and upward
• Many variations allow it to be versatile

Disadvantages

• Low reach compared to reverse bars and scissors

Reverse bar lifts are a variation of the bar lift that uses a bar lift attached to another bar lift facing opposite of the first lift. This allows the robot to reach somewhat higher than a typical bar lift and lift objects attached to the lift in a near vertical motion. Despite being a variation of the bar lift, reverse bars are slightly more difficult and time consuming to build as the mechanism connecting the two bar lifts on each side is usually some sort of gearbox that moves the second bar lift as the first one is moving.

Common variations of the reverse bar lift include:

• Reverse double 4 bar (RD4B)
• Reverse double 6 bar (RD6B)

Advantages

• Moderately high reach comparable to a two stage scissor lift

Disadvantages

• Moderately difficult to build

Elevator lifts uses linear motion to raise a set of linear slides vertically. The mechanism that achieves this motion varies from a rack and pinion gear to a pulley system. Elevator lifts are generally compact and stable lifts, however, the most prominent issue is the friction which can slow down the entire lift if not properly mitigated.

Advantages

• Stable
• Generally more compact than other lifts

Disadvantages

• Difficult to tune and optimize
• Friction from the linear slides can slow down the entire lift

Scissor lifts allow the robot to reach high places by a series of two c-channels attached together at the center called stages. These stages are attached at each end of each c-channel and stacked upon each another. Because of these stages, scissor lifts generally have the highest reach out of all the lifts. A four stage scissor lift made out of 1x2x1x35 c-channel can reach up to six feet high. The biggest drawback however is that scissor lifts are some of the most difficult types of lifts to build and require a large amount of material. Scissor lifts are also infamous for becoming unstable at higher levels. Robots with scissor lifts run the risk of tipping over due to the lift swaying sideways¹⁾.

Advantages

• Has the highest reach

Disadvantages

• Difficult to build
• Requires a large amount of material to build
• Can become unstable at higher levels

• List of Lifts (VEXForum)