No limits
to your design
We develop and build fully customized Inverted Planetary Roller Screws. LTK adapts to your needs, without compromise.
From Prototype to
large scale manufacturing
We enable fast development for your prototypes. Once you are ready, we provide fully automated and large scale manufacturing with a capacity of >5.000 individual pieces by dedicated machinery.
Full Electric Actuator Design available
Beyond standards we provide fully customized electric solutions on our Inverted Planetary Roller Screws. Check out more on: ACTOS – Customized Linear Actuators
The desired requirements for an actuator in robotics are:
- Compact design
- Low energy consumption = High efficiency
- High actuation force at all positions
- Short-Stroke, yet fast movements (e.g. to jump/run)
- Shock-impacts (to land / fall)
Firstly, Planetary Roller Screw fulfill the very basics requirements with a compact design, high efficiency, high linear speed and force already as a standard. Secondly, the inverted design allows the integration of encoder and drive.
Thirdly, the Planetary Roller Screws implements a gear reduction by the chosen thread, saving another part. Fourthly, the many contact points bring high rigidity into the system and give them increased shock-resistance.
Planetary Roller Screws date back to the late 1940, early 1950 and convert rotary motion into linear motion. The working principles are similar to Ball Screws, as the contact point of a planet is generated by grinding a radius, simulating a ball on every contact coint.
Planetary Roller Screws build their stand on the same characteristics as a Ball Screw (High Efficiency and Precision) and add value by allowing 3-5 higher load ratings. Therefore Planetary Roller Screws allow much smaller designs, compared to Ball Screw Technology.
Different to Ball Screws – Planetary Roller Screws allow by nature of the screw an inverted design. The typical way is linear motion of the „nut“, originated by rotary motion of the „spindle“ (similar to ball screws). This is analogous to ball screws, where the deflection system is within the nut. Planetary Roller Screws don‘t use deflection systems which allows a more compact design and the inverted design.
This allows the inverted design, where the nut moves rotary and the spindle linear. Several advantages come by this design:
- Bearing can be mounted onto the nut
- The shaft is very easy to adapt
- Drive system and encoder can be mounted directly on the screw
This design has by far the greatest advantages and several unique features. However it is also the hardest to manufacture. LTK has therefore decided to build their own machinery to enable maximum manufacturing efficiency.
The many number of contact points, that allow higher load ratings, also bring the challenge of a perfect fit. Accordingly all tolerances are very small and difficult to manufacture. Additionally all parts are made of pre-hardened steel to achieve higher rigidity and lifetime.
To achieve higher efficiency, LTK has developed and engineered dedicated equipment for planetary roller screws.
Not just the precision is a challenge, but also bringing all parts together by a gear ring, which holds the planets and spindle or planets and nut in Place.
All Planetary Roller Screws exist of at least these three components
- Nut with inner thread
- Spindle with outer thread
- Planets with outer thread
Depending on the design, several additional parts are added like gear rings, wipers, etc.
