LONG STROKE
RECIPROCATING MECHANISM
LSRM
The Long Stroke Reciprocating Mechanism (LSRM)
The US Patent number is 5,063,792, Nov 1991, owned by Dartnall
Engineering and Innovation Pty. Ltd. (Heliseal Pty. Ltd.). Extensive
R and D have continued based on this patent.
A
A
Pin and Slider
Yoke Mechanism
(two slider blocks)
Guide Rail
Chain or Belt
To Piston
Sprocket or Pulley
Carriage
A-A
The LSRM has proven advantages in reciprocating ground water
pumps and potential applications in pumping generally, gas
compression reciprocating engines and other linearly actuated
devices.
LSRM Engines (and other reciprocating machines)
Comparison of sizes
This is a short stroke engine and has only one quarter of the cubic
capacity of the three engines. This arrangement provides the basis
for the simplest construction and is widely used for small single
Conventional machines have used the crank and connecting rod to
cylinder engines. Stroke to bore ratio is limited to about two to one
link the output from the reciprocating piston to the rotating
to avoid fouling of the connecting rod with the cylinder wall.
crankshaft. This, standard arrangement is illustrated by the smallest
of the three engines below. (The engine on the right of the diagram.)
In the left side diagram, a cross head is added in order to extend the
stroke to bore ratio. In this configuration, a stroke to bore ratio of
about four to one is used in all modern large marine diesel engines.
The configuration is robust, allows excellent matching of engine
rotational speed and torque directly with propeller shaft speed and
torque requirements, and has produced the most efficient IC engines
in the world – typically about 50 – 54 % brake thermal efficiency.
The middle diagram shows the LSRM configuration, which would
give all the benefits of the crosshead configuration when
appropriately designed in a more compact and simpler package.
The LSRM configuration has already been successful in Dartnall
long stroke ground water pumps and has a future in other pumps as
well as gas compression and high efficiency, compact long stroke
engines.