By trolley, I am assuming you mean a passenger vehicle operating on a guide way with rails or other structure to restrain motion to a desired direction. The alternate definition: a pulley or truck running on an overhead guide way (such as the mechanism at the top of the pole mounted on trams or streetcars- often called trolley cars or trolleys at one time).It would require about the same constituents to operate either on an air track at constant velocity. Sufficient force would have to be exerted to overcome the force of gravity plus any other friction or pressure exerted by the guide way. This force could be exerted by the vehicle exerting a downward force (as hovercraft operate) or an upward force from the guide way suspending the vehicle. Once airborne, forward motion could be attained by the vehicle exerting force to the rear (Such as with a propeller, jet or rocket engine) or by force exerted against the guide way structure, by electric or other traction power. Constant velocity after overcoming initial inertia and friction would be maintained by exertion of constant additional power sufficient to overcome total air resistance (this is created by the air in front being pushed aside combined with friction of air flow along the vehicle surface plus the suction of the air pulled into the vacuum behind the vehicle) and friction of the guide way structure. Another possible power scheme is that used by magnetic-levitation railways, where the propulsion power is electromagnetic energy interacting between the vehicle and fixed structure. The experimental first subway in New York City, U.S.A. in 1869 was a vehicle propelled for one city block in a closed eight foot diameter tube by suction ( a large version of pneumatic tube systems later used to carry capsules containing messages in large government buildings and post offices and other institutions). The noted British engineer Isambard Kingdom Brunel experimented in 1847-48 with an "atmospheric railway" where trains were moved by a piston attached to the train's undercarriage and pulled by vacuum pressure through a 15 inch diameter pipe mounted between the rails of the track structure. The route tested was some miles in length and test trains attained speeds up to 68 miles per hour. Technical difficulties and unfavorable economic comparison to the cost of contemporary steam locomotive tractive power ended the operation. I am not sure the above answer is exactly what you seek, but I hope it gives you some ideas to consider.
Beach Pneumatic Transit - en.wikipedia.org, Isambard Kingdom Brunel - en-wikipedia.org