A stoneblower is a

railway Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a pre ...

track maintenance machine that automatically lifts and packs the

sleepers ''Sleepers'' is a 1996 American legal crime drama film written, produced, and directed by Barry Levinson, and based on Lorenzo Carcaterra's 1995 book of the same name. The film stars Kevin Bacon, Jason Patric, Brad Pitt, Robert De Niro, Dustin H ...

with small grade

ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship ...

, which is blown under the sleepers to level the track. An alternative to the use of a

ballast tamper Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship ...

, the totally self-contained machine levels track without the use of a large gang of workmen.

PBI'84

The Pneumatic Ballast Injection Machine was an experimental stoneblower tested by British Rail for the correction of

track ballast Track ballast forms the trackbed upon which railroad ties (sleepers) are laid. It is packed between, below, and around the ties. It is used to bear the load from the railroad ties, to facilitate drainage of water, and also to keep down veget ...

and vertical geometry. It was built by Plasser GB, a division of the Austrian railway machinery company

Plasser & Theurer Plasser & Theurer is an Austrian manufacturer of rail track maintenance and track laying machines. It accounts for 6% of Austrian exports of the machinery and iron and steel construction industry. History The company was established in 1953 by ...

under contract to British Rail. A "frog" device which attached ahead of the machine reported measurements one metre apart of the altitude, relative to the starting point, of each

rail Rail or rails may refer to: Rail transport *Rail transport and related matters *Rail (rail transport) or railway lines, the running surface of a railway Arts and media Film * ''Rails'' (film), a 1929 Italian film by Mario Camerini * ''Rail'' ( ...

head, at each sleeper, to an accuracy of 0.25 mm. Deflection indicators on each side reported height deviation at the 50 cm point between the two axles. Inclinometers on each side reported the angle from the horizontal, of the rail at that point. Electromagnetic sensors flagged the location of the steel

Pandrol Pandrol is a global rail technology company, founded in 1953 and operating in over 100 countries worldwide, with over 400 railway systems having adopted its products. A member of the Delachaux Group, Pandrol is based in Colombes, France and ...

clips which bind the rails to the sleepers. An onboard

Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president un ...

PDP-11 running the

RT-11 RT-11 (Real-time 11) is a discontinued small, low-end, single-user real-time operating system for the full line of Digital Equipment Corporation PDP-11 16-bit computers. RT-11 was first implemented in 1970. It was widely used for real-time computin ...

real-time operating system and FORTRAN would then calculate the distance each sleeper end would need to be raised; this was recorded as a quantity of stone that would hold the sleeper end at the new level. Stone Blower's

At each pair of sleepers, the machine lifted the track 50 mm and forced eight giant "hypodermic needle" points down to the level of the resulting temporary cavity below the sleepers. Four

Archimedes screw The Archimedes screw, also known as the Archimedean screw, hydrodynamic screw, water screw or Egyptian screw, is one of the earliest hydraulic machines. Using Archimedes screws as water pumps (Archimedes screw pump (ASP) or screw pump) dates back ...

s dispensed a measured quantity of gravel into the needles, and a jet of high pressure air at the back of the needle tip blew the stones into the cavity. Expected results were not achieved in practice,Kennedy A; Matharu M S
"PBI 84 assessment - A comparison with the Experimental Stone-Blower using the Rolling Load Rig facility (TM-TD-47)"
''Spark''. and British Rail continued to use the ballast tamper.

PBI'84

References

See also