Glossary of terms

Select a letter below to find a term that is used on this Web site that you may not be familiar with.

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All terms
+/-10V refers to a proportional reference signal that starts at OV in the middle of handle travel. In (1) direction the end of travel is +10V, at the opposite end of travel the reference is -10V.
Refers to a proportional reference signal for commanding a variable speed drive. The reference is OV at one end, 5V in the middle and 10V at the opposite end of handle travel.
4-20 MA
The 4-20 MA is a 2 wire transmitter model # ESS420 that delivers a 4MA to 20MA proportional signal over long distances or where power cables run with signal cables.
Absolute Encoder
An encoder who's count remains absolute at the count it was left at when power was disconnected and then restored.
Our air suspension system features APS "Automatic Positioning System." To operate, pull up on the operating handle and when the suspension moves, let go. The seat will automatically adjust to your weight for suspension ride. Operate the lever again without letting go and you can raise the seat to your desired height while retaining the same suspension ride.
Arc Suppression
The method of quenching an arc caused by the opening of a contact in the course of interrupting an inductive load.
Banana Handle
The type BH Banana Handle is shaped on a curve like a banana, so it always referred to this way.
The turning on and off of directional electro-hydraulic cartridge valves.
Back Electro-Motive Force is a term used to describe the phenomenon caused by a collapsing-electrical field. The voltage from the collapsing field can be harmful to electronic components.
Initial release
Cartridge Valve
An electro-hydraulic valve generally used to control the direction of hydraulic fluid flow.
Center Tap
A term used in describing a type of potentiometer. A conventional three terminal potentiometer with a tap at 50% of the resistance element electrical value is called a center tap potentiometer.
Command Signal
For proportional control a reference is used to control the amount an electronic device turns on. This reference is called the command for the electronics to change state.
Contact Drive
For the VNS series of 1 and 2 axis joysticks, the contact drive is the assembly that includes the cams, detent mechanism and contacts.
Contact Sequence
The arrangement of contact closures, i.e. cam cuts unique to a customer's control scheme.
Current Regulation
Our PFC/CR Electro-hydraulic valve driver cards compensate for load and power changes by keeping the current supplied to the valve constant.
A deadman is a safety device. Once the operator loses contact with a spring loaded button or similar device the function will stop.
Detent / Index
The mechanism on the joystick that gives the operator a feel for the handle position along its travel.
Differential Transformer
Our DGO rotary AC transforms are referred to as differential transformers. The secondary voltage is lower than the primary voltage and variable depending on where the core segment is rotated to.
Din Rail
Mounting rail for terminal blocks.
Direction of View
From your sitting position when looking forward is called the direction of view. This term is used when orienting joysticks that are not symmetrical for left or right orientation.
To turn off.
A low frequency signal superimposed on the valve to overcome hysteresis.
Dual Output Adjust. This is an option on our PFC electronic amplifier cards. This trimpot adjustment allows valve response to be set independent for each direction of full handle travel.
Double Acting Shock Absorbing
A shock absorber gas or hydraulic that provides the same dampening action whether extending or retracting. This type of shock is used in our seat suspension system.
Double Pole Contact Block
For NSO-O, NS2-O, VNSO, VNS2, and CSO our standard contact block houses two contacts.
Stands for Double Pole Double Throw. A contact with 6 terminals. The electrical content is equal to two SPDT contacts.
Dual Axis (two axis)
A joystick capable of operating two functions simultaneously.
A duty cycle is how many times the joystick is cycled per minute or per hour. This formula is used to determine the expected product life. A device that operates 100 times an hour is more likely to reach a high number of total cycles than one that cycles 1000 times per hour. If a joystick is rated for 20 million operations it is always recommended to qualify at what duty cycle was the rating derived.
Stands for electro-hydraulic proportional valves.
Eight Bit Gray Code
This is a code that was developed for optical encoders. The number of bits determines how many discrete counts or the resolution of the signal over a certain rotation angle. An 8 bit absolute encoder for J.R. Merritt Controls joysticks delivers 255 discrete counts in 120?.
EMI = Electro-Magnetic Interference. RFI= Radio Frequency Interference. These are types of electrical noise that can effect the performance of electronics.
To turn on.
The study of one's movements as they apply to their work.
Fore & Aft Adjustment
Our chair systems are configured with slides that allow the seat to move forward or backwards.
Four Wire Pot
Potentiometer with four terminals. The fourth terminal is tapped into the resistance element at 50% of electrical rotation.
Joysticks have gates mounted at the top or bottom of their housings to stop handle travel. Gates are also used to create special handle patterns for the operator to follow.
Gear Ratio
Our joystick have different gear ratios. The gear ratio is the potentiometer rotation divided by the full handle travel.
Gimbal Mechanism
See Yoke, two yokes operating with their axles in the same plane, but perpendicular to each other.
Hall Effect
Electronic-device that changes state when subjected to the presents of a magnetic field. Halls devices are commonly used as sensors, switches or provide a low level proportional signal.
Handle Deflection
The angle of movement of the handle shaft.
High / Low Range (Hi/Lo)
An option on our PFC electronic amplifier card. A trim potentiometer adjusts the low full-output performance which can also be switched to a different high full-output trim potentiometer setting.
Horizontal Drive
The contact drive assembly and output devices are mounted to the joystick housing in the horizontal plane.
The lag time in the response of the electro-hydraulic valve coil to the turn on signal.
Inadvertent Operation
The moving of a joystick handle by mistake. The mechanical interlock is furnished to prevent an inadvertent operation.
Incline or inclining angle commonly referred to an angle on many of our operator arm chair consoles. J.R. Merritt also offers a inclination adapter that allows for changing the angles of monitors to enhance operator ergonomics.
Inductively Coupled
A non-contacting system that picks up the effect of the relationship of a primary coil to a secondary coil. This signal is interpreted and amplified by electronics to provide a recognizable reference signal.
Light Emitting Diodes used on J.R. Merritt PFC electro-hydraulic amplifier for diagnostics.
Left Side Orientation
The mounting of a joystick so the operator can operate it while seated or standing from their left side.
Maintained Action
A joystick configured for step control without spring return. This joystick hunts from one detent position to the next and can be left in place.
Mechanical Interlock
Locks the joystick handle in place to prevent accidental operation. The operator must pull-up or push-down on the handle to release the lock.
A small self contained switch that can be mounted to the joystick to provide an off/on or directional signal.
Multiple Axis
A joystick capable of operating multiple functions via a single operating shaft.
Different degrees of sealing for enclosures and devices mounted in them.
Nickel Chromium
The material used in the gimbal yokes for NS & CS series joysticks. Nickel chromium has properties similar to stainless steel.
Electrical term for measuring resistance.
Operator Interface Systems (OIS)
A monitor with a touch screen or membrane switches that accepts operator inputs.
A hanging control console furnished with joysticks, push-buttons or rotary cam switches for use on overhead traveling cranes.
J.R. Merritt Controls' electro-hydraulic amplifier card is marketed as type PFC. PFC stands for proportional feathering control.
Pilot Devices
Push-buttons, selector switches and lights used in control panels.
An abbreviated term for potentiometer.
Pulse Width Modulation is a digital signal/wave form of off and on pulses. A transistor acts as a gate to control current flow. Switching the gate off and on at different rates changes or modulates the ratio of current and the pulse width.
Quick Connect
Referred to as Quick Connect or Quick Disconnect terminals. That are used to connect wire to microswitches or other devices with spade terminals.
Ramp is an option on our PFC Electronic amplifier card. Ramp is a delay in output from the normal output response. The purpose of this feature is to smooth out erratic operator operation that may damage equipment.
Ramp Rate
Time lag between the operators handle movement and the output response.
A voltage signal that is varied by the position of the joystick handle. This signal tells electronic drive cards for motors & electro-hydraulic proportional valves how much to turn on.
The distance the joystick handle moves compared to the value of the reference signal it outputs.
Right Side Orientation
The mounting of a joystick so the operator can operate it while seated or standing from their right side.
Rocker Handle
The RH and RHN Handle were designed specifically to have a momentary rocker switch mounted in the top.
Rotary Cam Switches
Our NSO-0, NS2-0 are rotary cam switches which evolved from our joystick products. The rotary switch can be utilized in the same applications as 1 axis Joysticks by providing step or stepless control of crane functions or process lines.
Saddle Clamp
A curved square clamp plate with a center hole. The clamp is secured by a machine screw. The wire is secured between the clamp plate and the device's terminal under pressure from the clamp screw.
Single Axis (one axis)
A joystick capable of operating one function via a single operating shaft.
A device such as a load that consumes power and conducts away heat.
A device that provides power to a load.
Stands for Single Pole Double Throw. A contact with three terminals 1 N.O & 1 N.C.
Stands for Single Pole Single Throw contact with two terminals 1 N.O.
Stay Put / Friction Brake
The joystick handle will hold its position anywhere along its travel. The resistance against movement is set at a tension that will prevent any change in position without operator influence.
A Joystick with a smooth handle action from center and back.
A joystick with graduated steps (detented positions) of the handle shaft movement.
Strain Relief
A device used to keep the strain caused by pulled wires and cables from effecting the terminal connections.
Switching Patterns
Patterns cut into the gate for the handle to follow.
Third Axis Twist
Proportional or off/on control can be added to the joystick shaft for a third axis of control.
Three Axis (3rd axis)
A two axis joystick with a third function added. A twist knob, rocker or thumb wheel can be added in place of the standard handle to provide an on/off or proportional third function.
Three Wire Potentiometer
A conventional potentiometer with a terminal at each end of travel. A center terminal is connected to an arm that moves between the end terminals, and is called a wiper.
Threshold (thres.)
An adjustment on our PFC electronic amplifiers that controls the amount of current available when the handle is moved just off center. The output is adjusted so the function shows minimum movement.
Trim Pots
These are small potentiometers used in our PFC electronics to adjust different output parameters.
Variable Speed Drives
SCR drives that are used to control the power of A/C and D/C motors.
Vertical Drive
The VNS series of 1 and 2 axis joysticks which have the contact assembly mounted below the operating head.
The connection piece in a joystick mounted between the operating shaft and the pivoting axles. The yokes provide the joystick with the ability to drive two functions simultaneously with a single operator movement.
Zytel Housing
Zytel is a Dow Chemical nylon elastomer. The CSO, CS2 and MO housings are manufactured from Zytel with glass fibers. This material has a low friction coefficient and remains stable over very cold or hot temperatures.