Hydraulic Power Brake Valve PDF02

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Product details

Hydraulic Power Brake Valve PDF02 Full Product Introduction

1. Basic Product Overview

PDF02 hydraulic power brake valve, also named hydraulic booster brake valve, is the foot-operated proportional control core matched with DACV dual-circuit charging valve and dual brake accumulators. It constitutes the full-hydraulic service brake assembly for engineering vehicles, delivering amplified brake pressure by foot pedal stroke. It outputs stepless proportional hydraulic oil to wheel brake calipers or the brake cavity of travel hydraulic motor, realizing flexible braking, creeping speed control and emergency stop. It is the mainstream upgrade alternative to traditional air-over-hydraulic brake systems, widely fitted on wheel loaders, road rollers, mining dump trucks, rough-terrain forklifts and heavy sanitation vehicles in the whole vehicle hydraulic system.

Model Explanation

- PDF: Series code for hydraulic foot-operated power booster brake valve

- 02: Upgraded heavy-duty version, optimized for high flow and frequent heavy braking; matched with dual independent accumulator circuits from DACV, featuring dual oil inlet ports for redundant safety design.

Differentiated from PDF01 light-duty version: PDF02 boasts larger internal flow passage, stronger pedal boosting ratio and better heat resistance for heavy-load frequent braking scenarios.

2. Core Technical Parameters

Item Specification

Product Type Foot Pedal Proportional Hydraulic Booster Brake Valve

Max Inlet Supply Pressure 21MPa (from DACV charged accumulators)

Max Output Brake Pressure 16MPa adjustable

Rated Output Flow 35L/min

Control Mode Mechanical foot pedal push rod proportional control

Circuit Configuration Dual independent supply inlets, dual brake output ports (front/rear axle split braking)

Valve Body Material High-strength cast aluminum alloy + forged steel valve spool

Sealing Kit Standard NBR oil-resistant seals; FKM high-temperature resistant seals optional

Compatible Hydraulic Fluid ISO VG46, VG68 anti-wear hydraulic oil

Operating Temperature -35℃ ~ +95℃

Core Functions Proportional brake boosting, dual-circuit isolation braking, automatic reset after pedal release, residual pressure retention

Warranty Period 1 year

3. Structure & Working Principle

Composed of pedal push rod assembly, proportional servo spool, dual independent inlet chambers, two brake output galleries and return oil passage. It connects to two accumulator outlets of DACV charging valve on the inlet side, and links front/rear axle brake actuators / hydraulic motor brake cavities on the outlet side:

1. Idle State (Pedal Released): Internal spool stays at home position; brake output ports communicate with return tank, no brake pressure built up, travel hydraulic motor runs freely without braking resistance.

2. Light Pedal Depressing (Gentle Braking): Push rod shifts the servo spool slightly, partially cutting off return oil and gradually connecting high-pressure accumulator oil to brake outlets. Small pedal travel generates low brake pressure for slow deceleration and creeping control.

3. Full Pedal Depressing (Emergency Heavy Braking): Spool fully shifts to block return oil completely; high-pressure oil from dual accumulators fully outputs to brake circuits to lock wheel hubs or hydraulic motor brake drums for rapid halting.

4. Dual-circuit Fault Safety: If one accumulator circuit fails and loses pressure, the internal isolation valve keeps the other intact circuit working independently to maintain partial braking capacity and avoid total brake failure.

5. Auto Reset: Release the brake pedal, built-in return spring resets the spool instantly, brake oil flows back to tank to fully release braking.

4. Core Product Advantages

1. Proportional boosting design: Brake output pressure strictly follows pedal travel, offering smooth braking feel without abrupt jolt, protecting hydraulic motor and transmission from impact damage.

2. Dual redundant oil supply matching DACV charging valve, complying with construction machinery safety standards; single-circuit breakdown cannot disable the whole brake system.

3. Integrated compact structure replaces bulky air brake cylinders and air-oil boosters, simplifying vehicle hydraulic system piping layout and reducing leakage points.

4. PDF02 upgraded flow design adapts to frequent start-stop heavy-duty operation, less prone to heat buildup and spool sticking compared to PDF01 light type.

5. Pure hydraulic mechanical structure with no electric components, highly reliable in dusty, muddy and low-temperature mine/construction sites.

6. Residual low-pressure retention design prevents brake caliper jitter and air ingestion in pipelines, prolonging service life of brake parts and hydraulic motor assemblies.

5. Typical Application Scenarios

1. Wheel loaders, motor graders: Matched with DACV charging valve to form full hydraulic brake system for front & rear axle split braking of travel hydraulic motor;

2. Heavy single-drum road rollers, small mining dump trucks: Main foot brake control for heavy-load downhill frequent braking;

3. Rough-terrain forklifts, port heavy stackers: Heavy cargo parking and running braking configuration;

4. Large sanitation sweepers, snow removal trucks: Special vehicle hydraulic brake original assembly or retrofitting replacement;

5. Refitting old machinery to eliminate air compressor and air pipelines, upgrading to full hydraulic brake scheme.

6. Fault Replacement Instructions

Replace complete PDF02 brake valve assembly for the following malfunctions: inconsistent braking strength between front and rear axles, no braking response despite pedal pressing, unable to release braking after lifting foot, serious oil seepage at push rod or port joints, and nonlinear unregulated brake pressure. Common causes include worn servo spool, cracked seals and fatigue failure of return springs.