Mechatronics is tough

Manual control

Non-automatic control in which, in contrast to automatic control, the task of at least one element in the control loop is taken over by humans.


The handshake is a communication protocol that controls the flow of data via the serial interface, for example between modem and PC. A distinction is made between hardware and software handshakes. The former switches a certain line (RTS / CTS) on the serial connection to stop or start the data flow. The second uses control characters inserted in the data stream (XON / XOFF).


In English referred to as "mobile phone" or "cellular phone". The word cell phone means "practical, useful" in English and has no connection with the phone.

Hard disk

Disk connected to a drive, the magnetic layer of which is applied to a solid carrier material such as aluminum or ceramic. See also under hard disk


Collective term for components and devices, i.e. the "hard" part of a computer system including the peripherals that physically exist in a system. This includes the CPU, memory, circuit boards, connectors, but also input points, screens and others.

Hardware handshake

The data transmission is not checked by control characters, but by the respective electrical status of separate handshake lines.


Ability of a steel to transform its structure into martensite by quenching after austenitization. A distinction is made between hardenability and hardening.


Resistance of the material to the penetration of a harder body such as a diamond or steel or hard metal.


Heat treatment of steel to increase the hardness by austenitizing and cooling.

Main line

In data technology, the main line is the main data transmission line in a bus system via which several local networks are connected to one another. In the electrical installation, the connection line between the transfer point of the distribution network operator (VNB) and the metering system is defined as the main line according to the technical connection requirements.

Main program

Part program marked with a number or identifier in which further main programs, subprograms or cycles can be called.

Main memory / working memory / RAM

Main spindle

Workpiece or tool carriers on machine tools with rotating cutting movements. Used in turning and cylindrical grinding machines for workpiece rotation. The tool is driven in drilling, milling and grinding machines as well as drilling and milling machines.

Main valve

In the case of pilot operated valves, the main valve is the actual working valve, which is actuated by the pilot valve, also referred to as the pilot valve.


HDTV is a digital TV standard for high-definition television that impresses with its sharp contours, brilliant colors and depth of field. HDTV is specified with 1080 lines interlaced (1080i) or 720 lines in full screen mode (720p) with an aspect ratio of 16: 9. The image resolutions for HDTV are 1280 x 720 pixels and 1920 x 1080 pixels. The difference in resolution compared to PAL television is 2.2 times that of 1280 x 720 and even five times that of 1920 x 1080. To receive HDTV you need a TV transmitter that broadcasts in HDTV and a set-top box (receiver) or a receiving device that can process, decode and play back the high-resolution signals (HD signals). Devices that are marked with HD ready or HDTV are suitable for displaying high-resolution signals. In order for a screen to be "HD ready", the following requirements must be met: at least 720 vertical lines, processing of the signals in full 1080 resolution, digital DVI or HDMI connection with HDCP copy protection and analog component connection YUV.


In the area of ​​e-mails or a newsgroup post, Head is the section in which general data such as sender, recipient, subject of the message or the dispatch route are recorded. The term head can also be found on hard drives. Here, the head (read / write head) means the magnetic read and write unit of a hard disk.

Hot storage grease

Hot storage greases are greases whose temperature range today is above 140 ° C (i.e. above lithium soap greases). Typical thickener systems for high-temperature greases are e.g. bentonite, aluminum complex, polyurea, PTFE.


Strongly temperature-dependent resistance with a non-linear characteristic curve, which becomes lower with increasing temperature. The thermistor is also known as NTC (negative temperature coefficient) and is used as a temperature sensor in measurement and control technology. The material used is polycrystalline semiconductors made from sintered metal oxides. A wide range can be set through the mixing ratio of different metal oxides. NTC thermistors are used, for example, to limit inrush currents. A thermistor in the supply line of an electrical device is cold before it is switched on, therefore conducts poorly and reduces the inrush current. After switching on, the resistor heats up very quickly and loses its high initial resistance. The opposite of thermistors are PTC thermistors, which conduct better at low temperatures and have a positive temperature coefficient.

shut down

Printout in the computer area for the proper end of a work session on the computer. In particular in Windows systems, where the "Exit" item is selected from the start bar before the computer is switched off, so that the current system settings are saved before the network connection is disconnected.

Auxiliary control loop

Control loop with which you can create additional help for the controlled system, such as an acceleration control loop. An auxiliary control loop does not have to be subordinate.

Auxiliary signals

All signals except the input signal that are required for the function and monitoring of a device. These include dither signals, feedback signals, test signals and others.

HL oils

Designation for hydraulic oils with aging and corrosion protection conditions for systems with high thermal loads. The viscosity index is 95-105.

HLPD oils

Non-standardized abbreviation for hydraulic oils with anti-aging, corrosion and wear protection additives as well as with emulsifying (dispersing) and detergent additives, which keep finely divided solid impurities and water droplets in suspension. The HLPD oil emulsifies up to about 2% water content. The viscosity index is 95-105.

HLP oil

Abbreviation for hydraulic oils with additives to protect against aging, corrosion and wear. Is used, for example, at high pressures where increased wear occurs. The viscosity index is 95-105.

High pressure area

In pneumatics, pressures above 10 bar are considered to be high pressure areas.

High pressure filter

Filter for installation in the pressure line of a circuit. With the high-pressure filter, the filter housing must be designed for the nominal pressure of the system, but not the filter element.

Boot up

Printout in the computer area for switching on the computer and starting the operating system.

Startup behavior

Transitional behavior of a drive motor when accelerating to working speed. The run-up time constant is of particular interest here, as is any overshoot.

Run-up time constant

Time for a drive motor to run up from standstill to a certain speed. A hydraulic motor reaches this speed much faster than an electric motor. For example, a hydraulic axial piston motor with 50 kW requires a run-up time of only about 0.2 s compared to an equally powerful electric motor with about 3 s.

High torque motors

Term for mostly slow-running hydraulic motors with a very large displacement and therefore very high torque. High-torque motors are usually designed as multi-stroke motors with a piston design.

High pass filter

Electronic circuit that allows high-frequency signals to pass through unchanged, but at low frequencies it causes amplitude attenuation and phase lead.

High-level language

Term for all problem-oriented programming languages. While the machine-oriented programming languages ​​such as B. Assembler, are hardly suitable for complex arithmetic tasks, the higher programming languages ​​or high-level languages ​​have the possibility of processing higher mathematical functions, output of texts, etc .

Maximum pressure

a) Upper limit of a pressure curve which briefly exceeds the calculation pressure and at which a device or system is still functional. The term maximum pressure is also used in hydraulics for a pressure range above approx. 600 to 800 bar.

Chaining up

Mounting form for hydraulic control valves in which the valves required for a function, e.g. B. directional control valve, flow control valves, check valves can be mounted on top of each other on the base plate.


Home to a web. This page is displayed by default when a server is accessed without specifying a page. But now it is often used synonymously for all Internet pages. As a rule, the homepage acts as a table of contents for an offer and gives an overview of the offer.

Hearing threshold

Sound pressure that the human ear can just barely perceive. The hearing threshold is frequency-dependent and lies in the range between 1 and 5 kHz. It varies from case to case, depending on whether it is determined with pure tones, noise of different bandwidths or tone pulses.


A host is a computer that allows users to communicate with other computers on a network through a communication program. See also under server. The host can be reached via a unique number (IP address). If several web servers are running on one computer, this can be equipped with several hosts.

HP (horse power)

American unit of achievement determined by a pulling horse. The unit HP (horsepower) was established by James Watt (1736-1819), the inventor of the steam engine, who after careful measurements found that a horse can lift 550 pounds at a rate of one foot per second. In relation to the SI unit of power, which is named after watts, this results in a conversion factor in which 1 HP corresponds to approximately 745.7 watts (not the same as the previous power unit PS, which converted into 735.5 W).


HTML is the abbreviation for "Hypertext Markup Language", the language of the World Wide Web. All WWW pages are based on HTML code, a simple "programming language" that defines, for example, the size and appearance of text and the position of images on a page. The so-called links, with which information and pages can be linked with one another, are also characteristic of HTML. A web browser such as Netscape or Internet Explorer is responsible for converting these commands into a finished page. Since they sometimes interpret the commands differently, it can happen that the same WWW page is displayed differently on different browsers.


HTTP is short for "Hypertext Transfer Protocol". All Internet addresses that begin with "http: //" are HTML documents, i.e. pages on the World Wide Web. In contrast to this, for example, FTP, the "File Transfer Protocol".


A hub is a coupler to which PCs are connected in a star configuration and networked. However, if there are too many PCs on a hub, there is a risk that they will interfere with each other during data transmission, since all data packets are sent to all computers at the same time. In such a case, a connection via switcher can help.

Hydrodynamic lubrication

A hydrodynamic lubrication is present when complete separation of the sliding surfaces by a film of lubricant is achieved during the movement sequence.


Hyperlinks are marked places in an HTML document (Internet page) that refer to another data file on the web. With a click of the mouse on a hyperlink, a wide variety of WWW pages that are present on the Internet can be accessed.


Hypertext is a text document with electronic cross-references to other text, image or other multimedia sources. By clicking on a referring hyperlink (text that contains links to other texts or documents), other sources (e.g. HTML, SGML, PDF) can be called up directly from the hypertext.

Specialized lexicon of mechatronics © 2005 Erich Käser. All rights reserved.