4 Friedrich Leutert GmbH & Co. KG
Engine Indicators Type 50 and Type 30 - Operating Instructions
1 The Engine Indicator
1.1 General Description
The LEUTERT engine indicator is used to draw a single graph of
the dynamic pressures in a combustion engine cylinder against the
cylinder volume. This so called a P-V curve or indicator diagram can be
used to diagnose problems such as leaking valves or incorrect timing.
The LEUTERT indicators can be used for any reciprocating engine.
To operate the indicator a sheet of paper is wrapped around the
drum. The indicator is mounted to the cylinder head of the engine
to be measured. The engine needs to be equipped with an indicator
valve to do so.
The indicator cord may be pulled manually to rotate the indicator
drum. The drum is returned by an incorporated spring. Alternatively
the cord may be connected to the cam shaft of the engine so that
the drum rotates backwards and forwards with the motion of the
piston. If connected to the cam shaft, the circumference of the graph
indicates the power of the cylinder.
A pen arm is linked to a spring bellow that is connected through
a pipe to a valve in the cylinder head. The pressure in the cylinder
head moves the pen along the axis of the drum to complete the
pressure volume graph.
The sectional drawing of the indicator shows that the bottom part is
mounted in the drum support by means of a slotted nut. Depending
on the expected maximum pressure, two types of bottom parts are
available: One bottom part for the piston rod 1/5 and one for the
piston rod 1/10.
The upper part consists of the recording mechanism, the piston rod
and the ring nut. The recording pencil of the indicator type 50 is
interchangeable. To be able to measure higher pressure, the LEUTERT
Indicators can be equipped with a smaller piston size. Corresponding
to smaller piston size, higher pressure ranges can be indicated with
the same spring.
The spring is a double-coiled, easily interchangeable tension spring.
All springs are precisely calibrated and marked with the spring number
corresponding to the max. pressure rating. When selecting springs,
note that the highest frequency of natural vibration can be obtained
by using the largest piston possible with appropriately strong spring.
Every single device is being tested and calibrated according to our
ISO 9001 quality standards and will be supplied with a calibration
certificate proving the accuracy of the device.
