Abstract: A mobile vacuum and pneumatic unit of the sort which is usually truck mounted and self-contained is disclosed. The unit usually has two independent tanks, side-by-side, and two vacuum units which may be operated independently or in aiding relationship. Generally, one of the vacuum units is a liquid seal pump operating at nearly 29 inches of mercury, and the other is a high volume blower operating at about 20 inches of mercury. Valving arrangements are provided whereby a three-way valve permits vacuum communication from an exhaust header duct connected to the tanks to either or both of the vacuum units; with an additional valving arrangement at the input side to the tanks to select either or both. The output of the blower may be returned to one or both of the tanks to pressurize them.