1. Product Overview
This 7-piston assembly is a core internal spare part for Rexroth A6VM200F bent-axis variable displacement piston motor. The whole set consists of 7 pistons, slippers, retainer plate, guide ball and related support components, matched with 24-tooth spline cylinder block. It converts hydraulic pressure into rotational torque, and transmits power through the 24-tooth internal spline to the output drive shaft. Widely applied on closed-loop hydraulic systems of rotary drilling rigs, road rollers, mining winches and tunneling machinery.
2. Complete Assembly Composition
1. Seven single pistons
2. Seven wear-resistant slippers (shoes)
3. Retainer plate (return plate)
4. Central ball joint / spherical guide head
5. Retaining spring assembly
6. 24-tooth internal spline matching interface (mated with cylinder block spline hub)
3. Structural & Material Features
Piston
- Material: High-strength alloy steel, surface carburizing quenching, mirror precision honing
- Surface coated with anti-wear solid lubricant coating, low friction, anti-scuffing
- Inner spherical surface fits slipper ball head to realize free swing during variable displacement
Slipper
- Copper alloy base with high wear-resistant friction layer
- Built-in micro damping hole for static pressure oil film lubrication between slipper and valve plate
- Effectively reduce friction heat and avoid dry grinding under low-speed / zero-speed standby
Retainer Plate
High-toughness alloy steel stamping forming, evenly holds 7 slippers, keeps synchronous follow-up with cylinder block rotation; cooperates with central spring to press slippers tightly against valve plate sliding surface all the time.
24-Tooth Spline Matching Specification
- Spline form: Involute internal spline
- Tooth quantity: 24 teeth
- Matched component: A6VM200F cylinder block central spline hub
- Function: Transfer full hydraulic output torque, bear alternating impact load under frequent forward/reverse rotation
4. Core Working Principle
When the motor operates, high-pressure oil pushes 7 pistons to extend outward along the inclined axis. The spherical structure of pistons and slippers converts linear reciprocating thrust into rotary driving force. The retainer plate locks all slippers to ensure consistent movement of each piston unit. Torque is transmitted outwards via the 24-tooth spline of cylinder block. The 7-piston layout makes pressure & torque pulsation smaller than 9-piston versions, running smoother with lower vibration.
5. Main Technical Parameters
- Displacement matching: 200 cc/rev (A6VM200F)
- Rated continuous pressure: 350 bar
- Peak instantaneous pressure: 420 bar
- Allowable rotating speed: Max 3200 rpm
- Spline: 24-tooth involute spline, standard Rexroth internal spline dimension
6. Common Failure Phenomena
1. Slipper friction surface scratching, ablation or metal peeling (oil contamination, insufficient charge pressure)
2. Piston outer cylinder surface scoring, large internal leakage, insufficient motor output power
3. Retainer plate deformation, slipper falling off, abnormal motor jamming and loud noise
4. Spline tooth surface pitting, abrasion or tooth collapse (overload impact, poor coaxiality)
7. Matching & Replacement Notes
1. Must be fully matched with A6VM200F motor, cannot be interchanged with A6VM215, A6VM160 and other displacement piston assemblies
2. The 24-tooth spline must be aligned with the cylinder block spline hub during assembly, no forced hammering
3. Replace the whole piston assembly set instead of single damaged piston/slipper separately to avoid uneven stress and premature wear
4. Before assembly, fully lubricate piston outer circle and slipper friction surface with corresponding hydraulic oil, strictly prohibit dry installation
5. Simultaneously inspect cylinder block, valve plate and bearing wear status while replacing the piston assembly
8. Typical Application Equipment
- Rotary head & main winch motors of rotary drilling rigs
- Travel motors for underground mining vehicles
- Drive motors of road milling machines and compactors
- Hoist motors for engineering cranes and tunneling equipment
