Neometrix / Rail Test Equipment / Pantograph Test Bench / NMX-PNT-75

NMX-PNT-75 · ENGINEERED-TO-ORDER CLASS — SPECIFY · MOUNT · MEASURE · BUILD · TEST · PROVE

Pantograph Test Bench. Too light arcs, too heavy wears.

Name: Pantograph Test Bench
Brand: Neometrix
SKU: NMX-PNT-75

A pantograph presses a contact strip against the overhead wire to collect current. The press is a force, set by the raising device and by the height at which the strip meets the wire.

So the bench has to measure the force at every height, in both directions, and try the dropping device and the air system that make a raised pantograph safe to leave.

Discuss a pantograph bench Capability note (PDF)

A single pantograph test bench on a plain white studio background: a heavy grey painted steel gantry with two square columns and a crossbeam, a bright flat contact bar hanging from a bright load cell, and on a grey base plate below it a single-arm pantograph in a folded Z shape of bright aluminium tubes with springs and a collector head with two black carbon strips touching the bar, and no people

Fig · 01 — A pantograph test bench: a gantry with a contact bar hung from a load cell, and a pantograph on an insulating base with its collector head touching the bar — illustrative render.

The force

at every heightgoing up and coming down

The raising

timed, and the loweringfrom a controlled air supply

The dropping device

tried with its real triggerand the way it drops recorded

The air

held, to test the drivea timed leak check

Status

engineered to orderno pantograph bench claimed

ISO 9001ISO 14001EN 50206-1 reference standard

Overview

Why the whole job is the force.

Because the wire feels only one thing from the pantograph, and that thing is a force.

A single single-arm electric locomotive pantograph on a plain white studio background, raised in a folded Z shape: a lower arm and an upper arm of bright aluminium tubes, bright steel springs, four grey ribbed insulating supports on a grey base plate, and a collector head with two black carbon strips, and no people

Fig · 02 — A single-arm pantograph on insulating supports: two arms, springs and a collector head with two contact strips — illustrative render.

Too light arcs, too heavy wears.

What the bench is for

It tests an electric locomotive pantograph away from the roof. It raises and lowers the pantograph against a contact bar that stands in for the wire, reads the force at the collector head, and times the raising and the lowering. It also tries the automatic dropping device and the air tightness of the drive. It suits a routine bench, a type-test bench and a combined bench with both.

Why too light arcs and too heavy wears

The strip has to press on the wire hard enough to stay in contact, and no harder. With too little force, the strip lifts off the wire for moments and the current arcs across the gap. With too much, the strip wears the wire faster.

Why the force is read at every height

The force a pantograph gives is not one number. It changes as the pantograph rises, because its springs and its air drive work through arms that change angle. The pantograph is therefore tried across the whole range of heights at which it works under the wire.

Why both directions are measured

Friction in the joints of the arms resists the motion, so the force going up differs a little from the force coming down. The bench measures both, because the pantograph meets the wire from below and also follows it down.

Why the dropping device and the air are tried

A pantograph that is left raised has to be safe. If the strip breaks or the air is lost, the automatic dropping device lets the pantograph fall back by itself.

The bench tries that device with its real trigger. It also times the raising and the lowering, and holds the air pressure to see whether the drive leaks.

What the bench does not measure

It measures the static force, with the pantograph still. On a running train the air adds to the force and the wire moves, so the force on the line varies from moment to moment. That is measured on the line, and it is not what this bench claims.

The method

Specify, mount, measure, build, test, and prove.

Six steps in a fixed order. Reading the force at the collector head, and measuring the friction of the bench itself, are the two a quick order skips.

1 · Specify

The pantograph types, the working height range, the range of force and the tests are stated by the customer.

2 · Mount

The base and fixtures hold each type as it sits on the roof, with its own air supply.

3 · Measure

The contact bar, the load cell and the height transducer are chosen so that the force is read at the collector head and not at the base.

4 · Build

The gantry, the drive, the base, the air supply and the console are built as one installation.

5 · Test

The bench is proved with a reference force, the friction of its own guides is measured, and the guards are tried, before any pantograph is run.

6 · Prove

A record is kept for every pantograph, with its force curves, its times and its leak hold, and handed over with the bench.

What the bench tries on a pantograph

Test	What it finds	What to watch
Static contact force across the height range	the vertical force the head applies at each height, going up and coming down	friction in the joints makes the up and down forces differ, so both curves are kept
Raising and lowering	the time the pantograph takes to rise to the wire and to come down, and how it behaves at the end of its travel	the air supply and its throttles set the times, so the bench feeds the pantograph from a supply it can control
Automatic dropping device	whether the pantograph drops by itself when the strip is damaged or the air is lost	it has to be tried with the real trigger, and the drop has to end without slamming
Air tightness of the drive	whether the drive holds its pressure	a leak slows the raising and can let the pantograph sag, so the test is a timed hold

The step people underrate is the friction of the bench itself. A bench whose own guides drag adds its own difference between up and down to the one it is trying to measure.

Work content

What the bench contains, element by element.

Read it as a checklist: a bench missing a row will pass a pantograph on paper and not under the wire.

A single pantograph collector head on a plain white studio background: a long rectangular bright aluminium frame carrying two parallel black carbon contact strips, with springs, a sprung support and a pivot block at each end and a short aluminium tube rising from the middle, and no people

Fig · 03 — A pantograph collector head: a rectangular frame with two carbon strips, sprung supports and a pivot block at each end — illustrative render.

Element	What it does	What matters
Gantry frame	carries the contact bar	stiff and square, so that the bar stays level as it moves
Contact bar and load cell	stand in for the wire and read the force	a flat bar with a load cell that reads the vertical force at the collector head, checked against a reference force
Height drive and transducer	move the bar	a slow, smooth drive that traverses the whole working height up and down, with the height read at the bar
Mounting base and fixtures	hold the pantograph	a base that matches the roof mounting of each type, so that the arms work as they do on the roof
Air supply and control	feed the drive	pressure and flow controlled and measured, so that the raising and lowering times mean something
Dropping device trigger	tries the automatic drop	a real trigger for the automatic dropping device, and a record of whether and how it dropped
Test console and record	run the tests	the force against height going up and coming down, the times and the leak hold, kept for every pantograph
Guards and interlocks	protect people	a guard round the arms, which are sprung and can move suddenly, and a door interlock that stops the drive when it is opened
Procedure	fixes the sequence	specify, mount, measure, build, test and prove, the same for every pantograph
Testing & documentation	prove the bench first	a reference force applied, the friction of the guides measured, and a record the customer can inspect

The elements that decide whether the bench can be trusted are the contact bar with its load cell and the friction of the bench itself. The force it reports can only be as good as the bar that reads it and the guides that carry it.

Full specification — expand

System	A heavy gantry with a movable contact bar and a load cell that read the vertical force at the collector head; a height drive and transducer; a mounting base and fixtures that match the roof mounting of each pantograph type; a controlled air supply for the drive of the pantograph; a trigger for the automatic dropping device; a test console with a record for every pantograph including the force against height going up and coming down, the raising and lowering times and the leak hold; guards and interlocks; a written test plan; and testing and documentation before handover
The One Idea	Too light arcs, too heavy wears.
Why Too Light Arcs And Too Heavy Wears	The strip has to press on the wire hard enough to stay in contact and no harder, because with too little force the strip lifts off the wire and the current arcs across the gap, and with too much force the strip wears the wire faster
Why The Force Is Read At Every Height	The force a pantograph gives is not one number, because it changes as the pantograph rises, since its springs and its air drive work through arms that change angle, so the pantograph is tried across the whole range of heights at which it works under the wire
Why Both Directions Are Measured	Friction in the joints of the arms resists the motion, so the force going up differs a little from the force coming down, and the bench measures both because the pantograph meets the wire from below and also follows it down
Why The Drop Device And The Air Are Tried	A pantograph that is left raised has to be safe, so if the strip breaks or the air is lost the automatic dropping device lets it fall back by itself, and the bench tries that device with its real trigger, times the raising and the lowering and holds the air pressure to see whether the drive leaks
What The Bench Does Not Measure	The bench measures the static force with the pantograph still, whereas on a running train the air adds to the force and the wire moves, so the force on the line varies from moment to moment, and that is measured on the line and is not what this bench claims
Standards	EN 50206-1 is the public standard for pantographs for main line rolling stock. It sets their characteristics and the tests they must pass, among them a measurement of the static contact force and a check of the operating system. This page prints none of its forces, heights, times or tolerances, and no edition year: those come from the standard the customer names and from the pantograph. Approval of a bench or of a pantograph rests with the customer and the authority they name; none is claimed here
Configurations	A routine bench for checks, a type-test bench and a combined bench with both modes and one record
Scope Boundary	This page is the pantograph test bench. It is not a speedometer test bench (see speedometer test bench), not a traction motor test bench (see traction motor test bench) and not a brake test rig, which proves air brakes at coach and train level (see single wagon, single coach and rake test rigs). A contact wire measuring car and a roof inspection platform are different equipment again. No certification is claimed here
Status	Neometrix engineers pantograph test benches to order, and no delivered pantograph test bench is claimed.

Configurations

One method, three ways to build the bench.

The method, the contact bar and the record are shared. What changes is how much of the test is automatic.

Routine bench

Manual mode for checks

A gantry, a contact bar and a load cell with manual control of the height, for the force check, the timing of the raising and lowering, and the leak hold on every pantograph that comes through the shed.

Type-test bench

Automatic mode for compliance

The same gantry with an automatic height drive and a controlled air supply, running the full cycle of tests and logging every curve, for a new design or a changed one.

Combined bench

Both modes, one record

A bench that runs in manual mode for checks and in automatic mode for type tests, with one record for every pantograph tried in either.

And the part that is not equipment at all, yet decides all three: the test plan. It fixes the heights at which the force is read, how the bench's own friction is checked, how the dropping device is triggered, and what is recorded. It is written from the pantographs, not from the gantry.

Where it is used

Wherever a pantograph is trusted again, and has to show its force first.

The common thread is a pantograph that has been stripped, repaired or changed, and has to go back under the wire without wearing it or losing contact with it.

Locomotive sheds

Where pantographs come off the roof for overhaul and must be proved before they go back.

Pantograph overhaul shops

Where pantographs are stripped, rebuilt and set, and each one needs the same curves and the same record.

Multiple-unit depots

Where many identical pantographs are checked in turn and a drifting one has to be seen early.

Manufacturers and acceptance

Where a new or repaired pantograph is proved before delivery, or accepted by the customer on arrival.

Watch

See it in motion.

A short walkthrough video of the pantograph test bench.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does a pantograph test bench actually do?

It tries a pantograph away from the roof. The pantograph stands on a base that matches its roof mounting, and a contact bar that stands in for the wire is brought down onto its collector head. The bench moves the bar through the working height range, up and down, and reads the vertical force at the head. It times the raising and the lowering, tries the automatic dropping device with its real trigger, and holds the air pressure to test the drive. It does not measure the force on a running train, and it does not inspect the contact wire.

Q · 02 Why does too light arc and too heavy wear?

Because the strip has to stay in contact with the wire without grinding on it. With too little force, the strip lifts off the wire for moments as the wire moves, and the current jumps the gap as an arc, which damages both the strip and the wire and spoils the supply. With too much force, the strip presses hard and wears the wire away faster. The right force sits between the two, and it has to hold across the whole range of heights at which the pantograph works.

Q · 03 Why is the force measured going up and coming down?

Because friction in the joints of the arms resists the motion in whichever direction it goes. Going up, the friction takes a little force from the strip. Coming down, it gives a little back. So the two curves differ, and a pantograph with stiff or dirty joints shows a wide gap between them. The bench keeps both curves for every pantograph, so that a stiff joint can be seen as a change in the gap, and so that the wire is met and followed with a force that is known in both directions.

Q · 04 What does the bench not tell me?

It tells you the static force, with the pantograph still. It does not tell you the force on a running train. At speed the air adds to the force, the wire rises and falls, and the contact force varies around its mean from moment to moment. That is measured on the line, with instruments on the pantograph. The bench is the check that the pantograph is set up correctly before it goes out, and it makes no claim about the dynamic force.

Q · 05 Is this the same as the speedometer bench, the traction motor bench or the brake test rigs?

No, and the differences are worth stating precisely. The speedometer test bench page covers checking a speed indicator against a reference. The traction motor test bench page covers running an overhauled motor under power. The single wagon, single coach and rake test rigs page covers air-brake testing at coach and train level. This page is the pantograph test bench. A contact wire measuring car and a roof inspection platform are different equipment again. It does not replace any of them, and it does not claim what they claim a second time.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix engineers pantograph test benches to order, and no delivered pantograph test bench is claimed. What stands behind the offer is adjacent: Neometrix engineers a speedometer test bench (see the speedometer test bench page), a traction motor test bench (see the traction motor test bench page) and railway air-brake test rigs (see the single wagon, single coach and rake test rigs page). The load cells, drives, transducers, air regulators and controllers are catalogue items, bought in, not invented. What Neometrix engineers is the bench around them: the gantry and mounting base, the air supply, the trigger, the console and the record, the procedure and the test plan. So the honest position is that the bench is engineered to order, the neighbouring disciplines are in the building, and the first bench of this exact kind will be built around the customer's own pantographs rather than taken off a shelf.

Q · 07 Which standard applies, and what can the bench not do?

EN 50206-1 is the public standard for pantographs for main line rolling stock. It sets their characteristics and the tests they must pass, among them a measurement of the static contact force and a check of the operating system. This page prints none of its forces, heights, times or tolerances, and no edition year: those come from the standard the customer names and from the pantograph. The bench tries a pantograph and keeps a record. It does not certify a pantograph or a locomotive: this page claims no certification or accreditation. No force, height, time or quantity figure is printed here, and approval for use rests with the customer and the authority they name; none is claimed here.

Q · 08 What do you need from us to quote?

Six things, and most of them describe your pantographs rather than the bench. First, the pantographs: the types to be tried and how many types there are. Second, the mounting: how each type is fixed to the roof, so that the base can match it. Third, the height range: the working heights across which the force must be read. Fourth, the air supply: how each type is raised and what the shed can provide. Fifth, the tests: the force, the timing, the dropping device and the leak check you want run. Sixth, the record: what you want kept for each pantograph. From that we come back with a bench concept, a written test plan you can check, and a budgetary price.

The neighbouring rail test pages, and how they differ from this one.

Three neighbours: one checks an instrument, one runs a motor, one proves brakes.

↗ An instrument

Speedometer Test Bench

Benches that check a speed indicator against a reference - an instrument bench, where this page tries a sprung arm and reads its force.

↗ A motor

Traction Motor Test Bench

Benches that run an overhauled traction motor under power and keep the record - a rotating machine, where this page tries a pantograph standing still.

↗ Brakes at train level

Single Wagon, Single Coach & Rake Test Rigs

Air-brake test rigs at coach and train level - a brake test, where this page checks the force and the air drive of a pantograph.

Browse all Neometrix product lines.

Get a quotation

Tell us the pantographs, the mounting,
and the heights you work at.

The projects desk replies within two working days with a bench concept, a written test plan you can check, and a budgetary quotation. Write to [email protected] or use the form.

Enquire — pantograph bench Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — PANTOGRAPH TEST BENCH SPECIFY · MOUNT · MEASURE · BUILD · TEST · PROVE — TOO LIGHT ARCS, TOO HEAVY WEARS ENGINEERED IN NOIDA · INDIA