Rexroth A4FM A6VM hydraulic motors for Sandvik DD310-40 drilling rig 77790050 77017641

The A4FM is a bent-axis, fixed-displacement piston motor. Unlike a variable unit, its swashing angle (and therefore displacement) is fixed at the factory, which means output speed and torque scale directly and predictably with input flow and pressure. There's no swashplate control mechanism to fail, which is part of why these motors have a reputation for being nearly bulletproof in harsh mining environments.

Typical Role on the DD310-40

On a rig like the DD310-40, fixed-displacement motors in the A4FM family are typically found driving:

Rotation units for the drifter, where a predictable torque-to-speed relationship simplifies control logic

Winch drives and other auxiliary functions where consistent output matters more than an adjustable range

Cooling fan drives, where simplicity and reliability trump flexibility

The A6VM is also a bent-axis piston motor, but its swash angle can be adjusted — usually hydraulically, sometimes electro-hydraulically — while the rig is running. This lets the same motor deliver high torque at low speed (maximum swash angle) and then shift toward higher speed at lower torque (reduced swash angle) as conditions change, without the operator touching a separate control.

Typical Role on the DD310-40

Variable motors in the A6VM family are the natural fit for:

Tramming/propulsion drives, where the rig needs massive torque to get moving on an incline or through debris, then wants speed once it's rolling

Feed and boom functions in some configurations, where the load varies significantly through the stroke

Any circuit paired with a variable-displacement pump, since matching a variable motor to a variable pump lets the whole circuit run closer to its efficiency sweet spot across a wider range of conditions

Control Types Commonly Seen

Depending on the specific DD310-40 hydraulic package, the A6VM's displacement control may be:

Pressure-compensated (DA control) — automatically reduces displacement as pressure rises, protecting the circuit from staling

Electro-proportional (EP control) — allows the rig's control system to actively manage displacement based on sensor input, common on rigs with more sophisticated onboard electronics

Maintenance and Reliability Considerations

Fluid Cleanliness Is Non-Negotiable

Axial piston motors have tight internal clearances between pistons, cylinder blocks, and valve plates. Contamination is the single largest driver of premature failure in both the A4FM and A6VM families. On an underground drilling rig, where dust ingress and hose/fitting wear are constant threats, filtration discipline (return-line and case-drain filtration, regular fluid sampling) matters more than almost any other maintenance variable.

Case Drain Monitoring

Both motor families should have case drain flow and temperature monitored, ideally with a flow meter in the return line during routine service checks. A rising trend in case drain flow, even without an obvious external symptom, is usually the earliest warning of internal wear.

Control Circuit Care (A6VM Specific)

For variable motors, the displacement control's pilot supply, orifices, and (on EP-controlled units) the proportional solenoid and its wiring deserve their own inspection line item. A perfectly healthy motor can look "faulty" simply because its control signal is compromised.

Seal and Shaft Care

Both families use shaft seals rated for the specific case pressure of the application. On a rig subjected to constant vibration and thermal cycling, seal replacement on a preventive schedule (rather than waiting for visible leakage) is generally cheaper than the resulting contamination and downtime from a seal failure.

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Q1: Which motor drives the DD310-40's tramming system?

A1: Tramming and propulsion functions typically use a variable-displacement motor from the A6VM family, since the rig needs high torque to start moving and higher speed once underway — exactly the range a variable motor is built to cover.

Q2: How do I know if a piston motor is wearing out versus a control problem?

A2: Rising case drain flow and temperature point toward internal wear (piston/cylinder or valve plate wear). A motor that won't reach its expected speed or torque despite normal case drain readings, especially on a variable unit, more often points to the displacement control circuit rather than the motor's core.

Q3:What is the price and delivery time of the Rexroth A6VM/A4FM motor for theSandvik drilling rig？

A3: The specific price and delivery time will depend on the equipment model or specific product model you provide.

Q4:How to purchase a Rexroth A6VM/A4FM motor for the Sandvik drilling rig?

A4:You can visit https://www.baolilaihydraulic.com/contact/ to contact us and purchase our products through various methods.