Abstract: A mobile apparatus for sequentially exchanging selected consecutive groups of oil ties in an existing railroad track for groups of new ties while retaining groups of old ties therebetween to support the mobile apparatus on the track, comprises at least one bridge-like work vehicle having a frame defining an upwardly recessed portion between respective ends thereof, and a succession of different individual devices mounted in the recessed frame portion of a respective work vehicle and operative to effectuate different sequential operations for exchanging the selected old ties for the new ties, the tie exchanging devices including at least two tie pulling and inserting devices arranged for longitudinal displacement within view of an operator's accommodation. A respective drive displaces each tie pulling and inserting device with respect to the work vehicle frame along a displacement path extending in the direction of the longitudinal extension of the work vehicle frame.

Abstract: In a mobile machine for tamping ballast under ties of a railroad track, which comprises a machine frame, spaced undercarriages supporting the machine frame for mobility on the railroad track in an operating direction, and a ballast tamping assembly mounted on the machine frame and comprising a vertically adjustable tamping tool carrier, a drive for vertically adjusting the tamping tool carrier, pairs of vibratory and reciprocatory tamping tools immersible in the ballast upon vertical adjustment of the tamping tool carrier, and drives for vibrating and reciprocating the tamping tools, the invention provides a vertically adjustable device associated with the ballast tamping assembly for gripping and transversely positioning a respective one of the ties, and a drive for vertically adjusting the device. A vertically adjustable ballast broom device preferably precedes the tamping tool assembly for sweeping ballast off respective ones of the ties into an adjacent crib defined between successive ones of the ties.