Topclad Length Measuring System (TLMS)

Topclad length measuring system (TLMS)

Now available with laser cladded coatings

Hydraulic cylinders are used in many different applications, where controlled forces and controlled stroke lengths are important functionalities, in addition to corrosion and wear resistance properties that are important for a long lifetime. TopClad TLMS has the capabilities to offer all of these functionalities by supplying ‘multi functional’ laserclad coating systems.

Often used field applications for cylinders with this type of high end coatings are:

  • Controlled hoisting
  • Accurate loading and unloading devices in the on- and offshore
  • Controlled dredging and digging equipment in the on- and offshore
  • Accurate positioning of lockgates in water ways (sluices), also in salt water applications
  • Control of bridges
  • Mining equipment, etc.


TLMS is a length measuring system for hydraulic cylinders up to 24.000mm long. It is based on a magnetic 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 that the cylinder rod moves along the sensor, the sensor will issue two pulses.

First at the beginning of magnetic field and secondly at the end. The distance between two magnetic fields is kept the same as the length of each individual magnetic field. In this way each individual signal (1/0 or 0/1) stands for a predefined fixed stroke lengths of the rod. The cumulated number of signals is the position of the cylinderrod.


By making grooves in the rod of magnetic steel, and so take away magnetic materials, the magnetic signal from the sensor is interrupted for each step that the rod is making. However, a cylinderrod needs to have a smooth surface, without grooves on the outside. Therefore, these grooves are filled by lasercladding with a non magnetic material. At the same time, the whole rod is covered with a laserclad coating to make the rod corrosion and wear resistant.


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 as shown in figure 1. In this way, a signal is generated each 1mm in stead 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 degree 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 is used.


Advantages of the TopClad Length Measuring System:

  • Low cost solution for a high quality laserclad coating, combined with a reliable length measuring system.
  • All types of Quarite and Tarisphere coatings from the Topclad program can be applied.
  • No restrictions on the length of the rod and so on the 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

More information:
Topclad B.V.