India is digging deeper and moving faster than ever before. The Tunnel Boring Machine (TBM) is an essential component that needs to function perfectly, hundreds of feet beneath the surface, whether it’s building extensions of the metro rail network in Mumbai, Delhi, Bangalore, Chennai or indeed tunneling highways through the Himalayas or railways like the Zoji La tunnel.
There’s no room for error when you’re underground. A TBM cannot be stopped for a road-side repair. Failure of a hydraulic component in a bore is not only a loss of time but also a loss of weeks of progress, stalled traffic corridors and huge rework costs. That is why a TBM’s hydraulic motor is so important.
At Polaris Hydrolicmotors, we design hydraulic motors for this kind of high-stakes and zero-failure environment.
TBMs rely on hydraulic power for their operation. Tunnel Boring Machines (TBMs) rely on hydraulic power.
Why Tunnel Boring Machines Depend on Hydraulic Power
A TBM isn’t a single machine — it’s a rotating cutterhead, a conveyor system, thrust jacks, and a segment erector all working in concert. Hydraulic motors are what make this coordination possible, as they provide:
Massive low speed, ideal for rotating a multi-ton cutterhead through rock, clay, or mixed ground conditions
Precise, variable speed control, allowing operators to adjust boring speed based on changing geology
Compact power density, since space inside a TBM shield is extremely limited
Continuous duty operation, often running 20+ hours a day for weeks without stopping
Electric motors struggle to deliver this combination of torque, control, and reliability in the confined, high-load conditions of a TBM. Hydraulics remain the industry standard for this reason.
Key Applications of Hydraulic Motors Inside a TBM
Cutterhead Drive Systems
The business end of the machine is the cutterhead, which requires tremendous starting torque to ‘bite’ into the rock and steady torque to keep the machine moving at the desired rate. This load is managed smoothly by hydraulic motors, as opposed to mechanical motors, which can cause mechanical shock that might lead to damage to cutting tools or drivetrain parts.
Thrust and Propulsion Systems
As the TBM advances, hydraulic cylinders and motors work together to push the shield forward against the tunnel face. This requires motors capable of handling high back-pressure without losing efficiency.
Conveyor and Muck Removal Systems
Excavated material (muck) has to be continuously transported out of the tunnel. Hydraulic motors drive the conveyor systems that keep this material flowing, even under heavy, abrasive loads.
Segment Erector and Auxiliary Systems
After boring the tunnel, the tunnel should be lifted and placed with precast segments with millimeter precision. Hydraulic motors provide the necessary fine control for this delicate, high-precision operation.
Key Characteristics of Hydraulic Motors Used by TBMs
Not all hydraulic motors are designed to operate within a tunnel boring machine. Infrastructure companies and OEMs should assess their supplier based on the following:
High torque-to-weight ratio — space and weight are always at a premium inside the shield
Contamination-resistant construction — dusty, abrasive environments are harsh on seals and internals, so choose components that resist contamination
Continuous-duty performance — TBMs often operate continuously and through several shifts
Reliable performance without derating under a range of conditions, from soft ground to hard rock
Reliable after-sales support — a stopped TBM costs money, so technical support and spare-parts availability are as important as the product itself
Why Indian Infrastructure Projects Need a Domestic Hydraulic Motor Partner
For years, Indian contractors have relied heavily on imported hydraulic components for metro, rail, and tunnel construction works. This means longer lead times, higher freight costs, and costly delays when replacement parts are urgently required on-site.
That’s where Polaris Hydrotechnik comes in. Being a hydraulic motor manufacturer from Maharashtra, we bring together:
Engineering precision backed by our parent company, Top Gear Transmissions
Faster turnaround time for replacement units and spares than overseas suppliers
Engineering designed for Indian conditions — dust, heat, and varying conditions on the land
Direct technical support so infrastructure teams do not have to wait for a foreign support desk
Building India’s Tunnels, One Rotation at a Time
Tunnel boring is one of the most demanding applications any hydraulic system can face — high torque, continuous duty, and zero failure, all happening in a space you can’t easily access once the operation begins. It’s an environment where the quality of a hydraulic motor is tested every single hour.
Polaris Hydrotechnik designs hydraulic motors engineered for this level of performance, helping India’s tunnelling and metro infrastructure projects maintain a reliable, locally supported power source.
Need a hydraulic motor solution for your tunneling project? Contact our engineering staff or check out our Alpha and Beta Series motors designed for heavy-duty industrial use.
Frequently Asked Questions
Q1. Why are hydraulic motors used in Tunnel Boring Machines instead of electric motors?
Hydraulic motors provide greater torque in a smaller package, maintain continuous high levels of torque without overheating, and provide smoother variable-speed operation, which are essential for cutterhead rotation and thrust systems within a tight TBM shield.
Q2. In India, which industries are using Tunnel Boring Machines?
The main areas of application of TBMs include metro rail projects, highway and railway tunnels, and utility tunnels, especially in major cities such as Mumbai, Delhi, Bangalore, and Chennai.
Q3. How often do a TBM’s hydraulic motors require maintenance?
This is related to hours of operation, ground conditions, and load levels, but motors operating under controlled contamination conditions generally require much less unplanned maintenance than standard industrial motors