Neometrix / Hydraulic Test Systems / Aircraft Brake Valve Test Bench / NMX-ASV-91

NMX-ASV-91 · ENGINEERED-TO-ORDER CLASS — SURVEY · SUPPLY · FIT THE VALVE · DRIVE · MEASURE · PROVE

Aircraft Brake Valve Test Bench. The outlet tells the truth.

Name: Aircraft Brake Valve Test Bench
Brand: Neometrix
SKU: NMX-ASV-91

An aircraft brake and anti-skid valve test bench proves, on the ground, the valves that stand between the pilot's pedal and the wheel brake: the brake metering valve, the anti-skid valve, and the shuttle and relief valves around them. It supplies clean hydraulic power, drives each valve the way the aircraft does, and measures the pressure that comes out. Neometrix engineers it as a system around the valve under test: the supply, the manifold, the drive, the measurement and the record.

So the bench has to supply clean fluid at a steady pressure and temperature, drive each valve as the aircraft drives it, and measure the outlet against the command.

Discuss an aircraft brake valve test bench Capability note (PDF)

A brake valve test bench on a plain white studio background: a waist-high pale grey steel bench on four castor wheels with a stainless work top and a closed cabinet of two plain doors beneath it, a flat pale grey test panel behind it with three small round gauges along its top edge, a stainless manifold block on the work top carrying a valve with a lever and a valve with a black electrical connector, bright stainless tubes to a small upright cylinder and a glass-tube flow meter, a controller box on a slim post at the left with a red emergency-stop button, and no people

Fig · 01 — A brake valve test bench: a test panel with a manifold carrying two valves, a small cylinder standing in for the brake and a flow meter, over a closed cabinet, with a controller box at its side — illustrative render.

The result

a valve proved on the groundits curve, its repeat and its leakage, on record

The supply

clean fluid at a steady pressurefiltered, held in temperature and checked for cleanliness

The drive

as the aircraft drives ita lever for the metering valve, a current for the anti-skid valve

The measurement

the outlet against the commandpressure, time and leakage, read the same way each time

Status

engineered to orderno delivered bench claimed

ISO 9001ISO 14001SAE ARP1070 referenceISO 4406 reference cleanliness code

Overview

Why two small valves are proved apart from the aircraft, and what the bench measures.

Because a brake that grabs, drags or leaks is usually a valve fault, and on the aircraft it is hard to say which valve it is.

Two brake valves on a test manifold on a plain white studio background: a blocky stainless manifold block on a pale grey base plate, a brake metering valve with a steel lever, a return spring and a slim rod to a small actuator cylinder on its left face, an anti-skid valve with a hexagonal coil housing and a black round electrical connector on its right face, two stainless gauge heads turned away on top joined by short bent tubes, and no people

Fig · 02 — The two valves on one manifold: a brake metering valve with its lever, and an anti-skid valve with its electrical connector, each on its own adapter plate — illustrative render.

The outlet tells the truth.

What the bench is for

It checks, off the aircraft, the valves of a hydraulic wheel-brake system: the brake metering valve that follows the pilot's pedal, the anti-skid valve that overrules it when a wheel starts to skid, and the shuttle and relief valves around them. It is used after an overhaul or a repair, and when a valve is suspected.

Why two valves decide the stop

The pilot's pedal sets the brake pressure through a metering valve. When a wheel begins to slow faster than the aircraft, a control unit tells an anti-skid valve to release some of that pressure, hold it, and let it return as the wheel speeds up again. So the pressure at the brake is the pedal's pressure as trimmed by the anti-skid valve.

Why the outlet tells the truth

A valve is good when the pressure at its outlet follows its command: the pedal movement for a metering valve, the current for an anti-skid valve. So the bench measures the outlet against the command. It records the curve, its width going up and going down, how closely it repeats, how fast the valve answers a step, and what leaks.

Why the supply is the hard part

The fluid has to be clean and held at a steady pressure and temperature, or the reading is the fluid's and not the valve's. So the supply is filtered finely, held in temperature, steadied by an accumulator, and checked for cleanliness against a particle code such as ISO 4406.

Why the load is a model of the brake

A brake is a volume that fills as the pressure rises. A valve working into a dead end looks better than it is. So the bench joins a model of the brake to the outlet, with a restrictor to set how fast it fills.

Why the answer is timed

Anti-skid control works only if the valve answers quickly, and SAE ARP1070 treats the response of the braking system as a first concern. So the bench records a step with a fast transducer against a time base, and not with a gauge and a stopwatch.

Why the leakage is measured at rest

A valve that leaks when it is told to do nothing lets the brake drag or creep. So the leakage at the outlet and at the return is collected and measured, and not judged by looking for a drip.

Why the record belongs to the valve

A reading is a reading and not a proof until it can be compared. So each valve's curves are kept against its own serial number, and the next overhaul is compared with the last.

The method

Survey, supply, fit the valve, drive, measure and prove.

Six steps in a fixed order. The supply and the proof are the two that a quick job skips.

1 · Survey

The valves to be tested are listed with their ports, their fluid, their working pressure and the test sequence in the maker's manual, together with the cleanliness and the record the shop needs.

2 · Supply

A pump, a reservoir, fine filters, a heat exchanger, an accumulator and the relief valves are sized for the largest valve and the steadiest reading, with a sample point for the cleanliness check.

3 · Fit the valve

A test manifold takes a quick-change adapter plate for each valve type, with the right ports for supply, return, outlet and drain, and a model of the brake on the outlet.

4 · Drive

A lever actuator moves the metering valve as the pedal does, with its force and travel measured, and a current source drives the anti-skid valve, with a small dither added where the valve needs it.

5 · Measure

Reference transducers read the curve and fast ones read the step, both at the outlet, and a metered collection reads the leakage, all logged by a controller that runs the sequence in order.

6 · Prove

The bench is checked against reference transducers and a known-good valve, the interlocks and the safe depressurising are exercised, and the record is handed over with the bench.

Which valve, which test

Valve	What it does	What the bench measures
Brake metering valve	turns the pilot's pedal movement into brake pressure	outlet pressure against lever travel and force, the width of the curve going up and down, the dead band, and the leakage at the return
Anti-skid valve	releases, holds and restores the brake pressure on command from the control unit	outlet pressure against current, null and threshold, hysteresis, the answer to a step, and the leakage when it is told to do nothing
Shuttle valve	chooses between the normal and the alternate supply	the pressures at which it moves, and its leakage in each position
Relief or pressure-limiting valve	limits the brake pressure	the pressure at which it opens and the pressure at which it closes again
Hydraulic brake unit (optional stage)	pushes the friction parts together	proof, external leakage and piston travel, but not braking torque, which needs a brake dynamometer

The step people underrate is the supply. A valve tested on warm, dirty or unsteady fluid shows the fluid's faults, and the valve takes the blame or the credit.

Work content

What the bench contains, element by element.

Read it as a checklist: a bench missing a row will test a valve, but it will not tell the shop whether the valve is right.

A complete valve test system on a plain white studio background: on the left a pale grey steel test bench with a stainless work top, a flat panel with one small gauge and a manifold block with two small valves on the work top, on the right a pale grey hydraulic power unit with a stainless filter housing, a finned heat exchanger, an electric motor and an upright accumulator on its reservoir, two braided hoses between them, a blank controller cabinet on a slim stand in the middle, and no people

Fig · 03 — The whole system: the test bench with its manifold and valves, the hydraulic supply beside it with its filters and heat exchanger, and the controller — illustrative render.

Element	What it does	What matters
Hydraulic supply	gives the valve its working pressure and flow	a pump and reservoir sized for the largest valve, with an accumulator to steady it and relief valves to protect it
Filtration and cleanliness	keep the fluid clean	fine filters in the supply and the return, a sample point, and a check of the particle code, so that the valve is not worn or blocked by its own test
Temperature control	holds the fluid at a steady temperature	a heat exchanger and a heater, because the viscosity of the fluid moves the reading
Test manifold and adapters	carry the valve under test	quick-change plates for each valve type, with ports for supply, return, outlet and drain, and a valve held in its working position
Lever actuator	moves the brake metering valve as the pedal does	smooth, repeatable travel, with the force and the position measured
Current drive	drives the anti-skid valve	a clean current that can be stepped or ramped, with dither where the valve needs it, and the current measured
Brake model and restrictor	stand in for the brake	a volume that fills as the pressure rises, and a restrictor that sets how fast, so that the valve works into a load and not a dead end
Pressure transducers	read the outlet	reference transducers for the curve and fast ones for the step, mounted at the outlet and checked against a reference
Leakage measurement	measures what the valve lets by	a metered collection at the return and the drain, read over a set time and not judged by eye
Controller and sequence	run the tests and keep them safe	runs the steps in the maker's order, logs the readings, and limits the pressure and the current to the valve's own limits
Frame, guard and containment	protect the operator and the shop	a guard around the valve, a drip tray, hoses routed clear, and a bench that cannot be opened while it is pressurised
Procedure and record	fix the test and keep the result	the same for every valve, with the curves kept against the valve's own serial number
Testing & documentation	prove the bench first	transducers checked, a known-good valve run, the interlocks and the safe depressurising exercised, and a record the customer can inspect

The elements that decide the result are the supply and the load, and the one that decides whether the shop can trust the reading is the record. The first two make the test fair, and the third makes it comparable.

Full specification — expand

System	A hydraulic supply with a pump, a reservoir, fine filtration, a heat exchanger and an accumulator; a test manifold with quick-change adapter plates and a model of the brake; a lever drive with force and travel measurement for the brake metering valve; a current drive with dither for the anti-skid valve; reference and fast pressure transducers; a metered collection for leakage; a controller that runs the sequence and records the result; a guarded frame with fluid containment; a written procedure; a record for each valve; and testing and documentation before handover
The One Idea	The outlet tells the truth.
Why The Outlet Tells The Truth	A brake valve is good when the pressure at its outlet follows its command: the pedal movement for a metering valve, the current for an anti-skid valve. So the bench measures the outlet against the command, and its width up and down, its repeat, its answer to a step and its leakage, and not the look of the part
Why Two Valves Decide The Stop	The pilot's pedal sets the pressure through a metering valve; when a wheel starts to skid, an anti-skid valve between the metering valve and the brake releases, holds and restores that pressure on command from a control unit; the brake pressure is the pedal's pressure as trimmed by the anti-skid valve
Why The Supply And The Load Matter	The fluid must be clean and held at a steady pressure and temperature, or the reading is the fluid's; and the valve must work into a model of the brake that fills as the pressure rises, because a dead end flatters it
Standards	SAE ARP1070 covers the design and testing of antiskid brake control systems and ISO 4406 covers the coding of the level of solid-particle contamination in hydraulic fluid. This page prints none of their procedures or limits, and no edition year: those come from the valve maker's manual and the standard the customer names. Approval of a bench rests with the customer and the authority they name; none is claimed here
Configurations	A bench for brake metering and shuttle valves, a bench for anti-skid valves, and a combined bench with a brake-unit stage
Scope Boundary	This page is the aircraft brake and anti-skid valve test bench, which proves the hydraulic valves of a wheel brake. It is not an aero-engine servo valve test bench, which proves the servo valves of an engine's fuel system on turbine fuel (see aircraft servo valve hydraulic test equipment), not an aircraft tyre nitrogen charging rig, which fills the tyre (see aircraft tyre nitrogen charging rig) and not a landing gear testing and charging rig, which works on the strut (see testing and charging test rig for main and nose landing gears). It does not test the electronic control unit, and it is not a brake dynamometer. No certification or accreditation is claimed here
Status	Neometrix has quoted against successive aircraft brake and anti-skid valve test bench requirements, and no delivered aircraft brake and anti-skid valve test bench is claimed.

Configurations

One method, three ways to build the bench.

The method, the supply, the measurement and the record are shared. What changes is which valves the bench has to drive, and how fast it has to read them.

Bench for brake metering and shuttle valves

A lever drive and a clean supply, for the valves that follow the pedal

For a shop that overhauls metering, shuttle and relief valves: a lever actuator with force and travel measured, a test manifold, a model of the brake and a leakage collection.

Bench for anti-skid valves

A current drive and a fast time base, for the valves that overrule the pedal

For the electro-hydraulic anti-skid valve: a clean current source with dither, a fast transducer at the outlet, a step test against a time base, and the null and threshold checks.

Combined bench with a brake-unit stage

Both valve types and a hydraulic stage for the brake unit, on one supply

For a shop that handles the whole hydraulic side of the brake: both drives on one supply, and a stage that proves the brake unit for leakage and piston travel.

And the part that is not equipment at all, yet decides all three: the survey and the test plan. They fix the valves, the fluid, the order of the tests, the limits and the record. They are written from the customer's own manuals and shop, not from the bench.

The drawings

A reference set, drawn as real CAD sheets.

Two sheets of one reference configuration: the process and instrument schematic of an aircraft brake valve test bench, and its general arrangement with three details. They show the supply, the test manifold, the two drives, the outlet and its transducers, the model of the brake, the curve and the answer to a step. They carry tags and letters only. Every pressure, current, flow, time and size is fixed by design for the customer's valves and manuals.

Reference drawing sheet one, the process and instrument schematic of an aircraft brake valve test bench. A controller sits above the whole circuit. On the left a hydraulic supply unit holds a reservoir, a motor and pump, a check valve, a fine filter, a relief valve, an accumulator, a pressure control valve, a heat exchanger and a return filter. A pressure line runs through an isolating valve to a test manifold that carries the valve under test, with a lever actuator and a current drive above it, ports for supply, return, outlet and drain, and a drain through a metered collection. From the outlet a reference transducer, a fast transducer and a restrictor lead to a model of the brake. A particle counter and a temperature sensor read the fluid. Instruments report to the controller. A legend, a table of holds and releases, ten notes and a title block stamped reference configuration, not for construction

Fig · 04 — Sheet 01, the process and instrument schematic: the hydraulic supply, the test manifold, the two drives, the outlet with its two transducers, the model of the brake and the leakage collection. Reference configuration, tags only.

Reference drawing sheet two, the general arrangement and details of an aircraft brake valve test bench. An elevation of the test bench shows a cabinet on castors with two doors, a work top with a drip tray, a test panel with a guard, a test manifold with two adapter plates, a brake metering valve with a lever and a lever actuator, an anti-skid valve with its coil housing and connector, a model of the brake standing on the work top and a controller on a post, with dimension letters for its height and width. An elevation of the hydraulic supply unit shows a reservoir, a motor and pump, a fine filter, a heat exchanger and an accumulator, with a pressure hose and a return hose. An item list numbers thirteen parts. Detail A is the curve of outlet against command going up and coming down, with its width. Detail B is the answer of the outlet to a step of the command, with its dead time and its rise time. Detail C is a section through the model of the brake with its piston and spring. A title block stamped reference configuration, not for construction

Fig · 05 — Sheet 02, the general arrangement and details: the bench and the supply unit in elevation, the curve, the answer to a step and the model of the brake. Reference configuration, letters only.

Every real bench is drawn for its own valves, fluid and shop. These sheets are the arrangement and the order of control that a project set starts from. Approval of any drawing rests with the customer and the authority they name; none is claimed here.

PDF · two sheets

Reference drawings — schematic and arrangement

PDF · capability sheet

Aircraft brake valve test bench — what Neometrix engineers

Where it is used

Wherever a brake valve has to be trusted again, and the shop has to show why.

The common thread is a valve that has been opened, repaired or doubted, and a result that has to be shown and kept.

Overhaul and repair shops

Where each valve is proved after overhaul, before it goes back to stock.

Valve makers and indigenisation work

Where a new or re-engineered valve is compared with the curve of the original.

Line-maintenance support

Where a valve taken off on suspicion is checked on the ground to see whether it is the fault.

Test laboratories and training

Where the behaviour of the valves is studied, or taught, on a bench that shows it.

Watch

See it in motion.

A short walkthrough video of the Aircraft Brake Valve Test Bench.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does an aircraft brake valve test bench actually do?

It proves, on the ground, the hydraulic valves of a wheel brake. A supply gives the valve clean fluid at a steady pressure and temperature. A drive works the valve as the aircraft does: a lever for a brake metering valve, a current for an anti-skid valve. A model of the brake loads the outlet, transducers read what comes out, and a controller runs the tests in order and keeps the result. It does not decide what a good valve is. The limits come from the valve maker's manual and the customer, and the bench holds to them.

Q · 02 Why two valves, and why measure at the outlet?

Because in a conventional hydraulic brake system the pilot's pedal sets the pressure through a metering valve, and an anti-skid valve between the metering valve and the brake trims that pressure when a wheel starts to skid. The control unit watches the wheel speeds and tells the anti-skid valve to release, hold and restore. So the pressure at the brake is set by two valves, and if the anti-skid action fails, the pilot is left with the metering valve alone. A valve is good when its outlet follows its command, so the bench measures the outlet against the pedal movement or the current, and records the width of the curve, its repeat, its answer to a step and its leakage.

Q · 03 Why does the supply matter so much, and why a model of the brake?

Because the valve cannot be judged on fluid that is dirty, warm or unsteady: the reading is then the fluid's, and a fine clearance can be worn or blocked by the test itself. So the supply is filtered finely, held in temperature, steadied by an accumulator and checked against a particle code such as ISO 4406. The model of the brake matters for the same reason. A brake is a volume that fills as the pressure rises, and a valve working into a dead end looks better than it is. So the outlet is joined to a volume that fills, with a restrictor that sets how fast, and the valve is judged working into a load like the real one.

Q · 04 Why is the response timed, and the leakage measured at rest?

Because anti-skid control depends on a quick answer, and SAE ARP1070 treats the response of the braking system as a first concern, to be considered early. A gauge and a stopwatch cannot show it. So the bench steps the command and records the outlet with a fast transducer against a time base, and the answer is kept with the valve's other curves. The leakage is measured at rest for a different reason. A valve that leaks while it is told to do nothing lets the brake drag or creep. So the leakage at the outlet and at the return is collected over a set time and measured, and not judged by looking for a drip.

Q · 05 Is this the same as the servo valve bench, the tyre charging rig or the landing gear rig?

No, and the differences are worth stating precisely. The aircraft servo valve hydraulic test equipment page covers a bench for the servo valves of an engine's fuel system, run on turbine fuel. The aircraft tyre nitrogen charging rig page covers filling the tyre. The testing and charging test rig for main and nose landing gears page covers the strut. This page is the aircraft brake and anti-skid valve test bench, which proves the hydraulic valves of the wheel brake. 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 has quoted against successive aircraft brake and anti-skid valve test bench requirements, and no delivered aircraft brake and anti-skid valve test bench is claimed. What stands behind the offer is adjacent: Neometrix engineers a servo valve hydraulic test bench for an engine's fuel system (see the aircraft servo valve hydraulic test equipment page), an aircraft tyre nitrogen charging rig (see the aircraft tyre nitrogen charging rig page) and a testing and charging rig for landing gear struts (see the testing and charging test rig for main and nose landing gears page). The pump, filters, transducers, actuator, current source and controller parts are catalogue items, bought in, not invented. What Neometrix engineers is the system around the valve under test: the survey, the supply, the test manifold and its adapters, the drive, the measurement, the sequence, the procedure and the record. 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 valves and manuals rather than taken off a shelf.

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

SAE ARP1070 covers the design and testing of antiskid brake control systems and ISO 4406 covers the coding of the level of solid-particle contamination in hydraulic fluid. This page prints none of their procedures or limits, and no edition year: those come from the valve maker's manual and the standard the customer names. The bench proves the hydraulic valves of a wheel brake. It does not test the electronic control unit, it is not a brake dynamometer and so it does not measure braking torque, and it does not replace the shop's own approved procedure: this page claims no certification or accreditation. No pressure, current, flow, time, size 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 valves rather than the bench. First, the valves: which types, their ports and their working limits. Second, the fluid: which one the valves use, and how clean it has to be. Third, the tests: the sequence and the limits in the maker's manual, and any test of your own. Fourth, the drive: the lever travel for a metering valve, and the current and dither for an anti-skid valve. Fifth, the shop: the space, the power and the cooling. Sixth, the record: what you want kept for each valve. From that we come back with a bench concept, a written test plan you can check, and a budgetary price.

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

Three neighbours: one proves engine servo valves, one fills the tyre, one works on the strut.

↗ Engine servo valves

Aircraft Servo Valve Hydraulic Test Equipment

A bench for the servo valves of an engine's fuel system, run on turbine fuel - where this page proves the hydraulic valves of the wheel brake.

↗ The tyre

Aircraft Tyre Nitrogen Charging Rig

Fills the tyre with nitrogen - the other end of the wheel from the brake valves this page proves.

↗ The strut

Testing and Charging Test Rig for Main and Nose Landing Gears

Works on the landing gear strut - a different job from proving the valves of the brake.

Browse all Neometrix product lines.

Get a quotation

Tell us the valves,
and the tests they must pass.

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 — aircraft brake valve test bench Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — AIRCRAFT BRAKE AND ANTI-SKID VALVE TEST BENCH SURVEY · SUPPLY · FIT THE VALVE · DRIVE · MEASURE · PROVE — THE OUTLET TELLS THE TRUTH ENGINEERED IN NOIDA · INDIA