Hydraulic Brake Pressure Test Rig

Every driver trusts that a light foot on the pedal becomes tonnes of clamping force at the disc — hydraulic advantage doing its quiet work through the master cylinder, the lines and the caliper pistons. In the classroom this is a formula: force times area ratio. In the lab it is almost never measured, because real brake systems are sealed, safety-critical assemblies that students cannot instrument. The gap is a dedicated, safe, open test rig where the whole chain is visible and every variable is measurable: pedal force in, line pressure through the system, clamping behavior out. This project builds it: a master cylinder actuated by a lever-type pedal with a spring-scale/load-cell force input, rigid lines to a brake caliper on a rotor disc, a bourdon-tube pressure gauge teed into the line, and a frame that holds everything rigid for repeatable tests. The student varies pedal force, reads pressure, and plots the system's actual pressure-vs-force characteristic against theory.

1. The student bleeds the system per the procedure until the pedal is firm — no compressible air in the lines.
2. A known force is applied to the pedal through the spring scale/load cell; the lever multiplies it into the master-cylinder pushrod.
3. The master cylinder pressurizes the brake fluid; pressure transmits equally through the lines (Pascal's law).
4. The bourdon gauge teed into the line reads the live hydraulic pressure; the caliper pistons clamp the rotor with force proportional to pressure times piston area.
5. The student records paired readings (pedal force, line pressure) across a stepped force series.
6. The data is plotted against the theoretical pressure from the bore-area ratios, and the deviation is analyzed honestly in the report.

Tech stack:

• Brake master cylinder with reservoir
• Pedal lever assembly with pivot and return spring
• Brake caliper + rotor disc
• Bourdon-tube hydraulic pressure gauge (teed into line)
• Spring scale / load cell for pedal-force input
• Steel-braided / rigid brake lines with fittings
• Welded steel test frame
• Brake fluid, bleed kit and service tools
• Test procedure with data-logging sheets

• [Master cylinder + pedal lever] A real brake master cylinder driven by a pivoted pedal lever; the lever ratio is a documented, measurable part of the mechanical advantage chain.
• [Live pressure gauge] A bourdon-tube pressure gauge teed into the hydraulic line shows line pressure in real time as the pedal is pressed.
• [Caliper and rotor assembly] A brake caliper gripping a rotor disc completes the real system chain — students see clamping happen as pressure rises.
• [Measured pedal force input] Pedal force is applied through a spring scale or load cell, so every test point pairs a known input force with a gauge pressure reading.
• [Bleed and service procedure] The kit includes the proper brake-fluid bleeding procedure — because air in the lines is the classic reason student rigs read wrong, and the report should say so.
• [Theory-vs-measurement plots] The procedure guides the student to plot measured pressure against the Pascal's-law prediction from cylinder and caliper bore areas.
• [Rigid test frame] A welded/bolted steel frame holds the cylinder, caliper and rotor in fixed alignment so tests are repeatable across runs.

• Working brake-pressure test rig (cylinder, pedal, lines, caliper, rotor, gauge, frame)
• Fabrication drawings and assembly documentation
• Hydraulic schematic of the test circuit
• Bleed and service procedure
• Stepped test procedure with data-logging sheets
• Component list with ratings
• Project report PDF (brake hydraulics theory, rig design, methodology, student's plots)
• PPT presentation for final review
• Viva Q&A preparation document (Pascal's law, hydraulic advantage, brake system basics)
• Setup and demonstration guide

• This is a static test rig, not a vehicle brake system: the rotor does not spin under load and no stopping-distance or fade claims can be made — the report scopes it as a pressure/transmission study.
• All performance figures are the student's own gauge readings; bore wear, seal condition and bleed quality all affect results, and the report must present them as measured.
• Brake fluid is hygroscopic and corrosive to paint; handling, spill and disposal notes are part of the safety documentation and must be followed.
• The gauge reads line pressure at its tee point; it does not measure caliper clamping force directly — that is derived, and the derivation's assumptions are stated.
• Air in the lines invalidates every reading; the bleed procedure is not optional, and the report should include a "with air vs bled" comparison as honest data.