A four-wheel
pool cleaner (20) motivated by
water flow to move along a
pool surface, and having: a body (24); the four wheels rotatably mounted thereon and including two sets of two wheels (22) each, one wheel of each set on each side; a drive mechanism (36) in position to be moved by
water flow and having a rotatable drive member (76); a drive
train extending to the first wheel set (22a, b) and to the second wheel set (22c, d), to drive all four wheels. Preferred embodiments include: wheel-to-
wheel drive links (88) along the side; a
turbine (36) as drive mechanism; a pair of spaced wheelgears (32, 34), preferably integrally formed with the wheel, facilitating drive linkages and steering; a pair of end-to-end drive shafts (80, 82) joined by a coupler (84c), one shaft end (80a) being a
ball joint allowing fore-and-aft movement of a drive-shaft distal end; a spring (102) and
cam (100) for alternately moving that distal end between a driving position engaging one of the spaced wheelgears (32), and a steering position engaging the other of the spaced wheelgears (34); wheel treads (108) with radial fingers (110), some (110a-c) of longer length; and a segmented articulated skirt (56) to help enclose a plenum beneath the
pool cleaner.