Topclad Length Measurement System (TLMS)

Topclad Length Measurement System

An improved Bosch Rexroth CIMS (Ceramax Integrated Measuring System)

TLMS is a length measuring system for hydraulic cylinders up to 24.000mm long. It is based on a sensor that recognizes small interrupted magnetic fields along the cylinder rod. These interrupted magnetic fields are positioned on fixed distances over the full length of the rod. At the moment the cylinder rod moves along the sensor, the sensor will issue two pulses. First at the beginning of the magnetic field and secondly at the end. The distance between two magnetic fields is kept the same over the full rod length. In this way each individual signal (1/0 or 0/1) stands for a predefined fixed stroke length of the rod. The cumulated number of signals is the position of the cylinder rod.

Topclad Length Measurement System (TLMS) 1

Magnetic fields

By making grooves in the rod of (magnetic) steel, the magnetic signal from the sensor is interrupted for each step that the rod is making. However, a cylinder rod needs to have a smooth surface, without grooves on the outside. Therefore, these grooves are filled by laser cladding with a non magnetic material. At the same time, the whole rod is covered with a laser clad coating to make the rod corrosion and wear resistant.

Topclad Length Measurement System (TLMS) 2
Topclad Length Measurement System (TLMS) 3


The sensor is a standard device, produced by several manufacturers. TopClad uses the Lenord+Bauer Gel 2478 for testing. This device is executed with two signal pattern functionalities, to be used on pitches of 4mm. In this way, a signal is generated each 1mm instead of a signal per 2 mm stroke length.

The accuracy of measuring can be further increased by applying more sensors, positioned on e.g. 90 degrees from the first one and phase shifted related to the first one.

The distance between the sensor and the surface of the rod (the air gap) might go up to 0,8 mm without loosing signals. Standaard a 0,5 mm air gap or less is used.


Low cost solution for a high quality laser clad coating, combined with a reliable LMS
All types of Quarite and Tarisphere coatings from the Topclad program can be applied
No restrictions on the length of the rod and consequently, on the length measuring system
High level of accuracy
No calibration needed
Extreme long lifetime
Easy serviceability, maintenance from outside the oil compartment
To be connected to all types of electronic (customized) devices


• Controlled hoisting
• Accurate loading and unloading devices
• Controlled dredging and digging equipment
• Control of bridges
• Mining equipment
• Accurate positioning of lockgates in water ways