Over the years, several new pieces were introduced in this line as well. The new pump was spring based, and could only be operated by hand, which limited pneumatic power to how fast it could be manually pumped. This obviously limited the power of pneumatic circuits. So in 1992, LEGO introduced two new pieces; a small pump and a small cylinder. The small pump did not have a spring on it, and it was designed to be operated by a motor, which would allow for continuously-running pneumatic creations. As of 2011, the small pump has only appeared in one set — 8868 Air Tech Claw Rig (1992) (found on Peeron) — and a few parts sets (no longer available). A new version of the small pump was released in Lego set 8110 Unimog U400 (2011). At 2L, this pump's stroke is 1/3 longer than the old one's 1.5L, 'L' being the LEGO unit of a stud. This made it much easier to use in studless construction.