WHAT TBS SYSTEM IS?
TBS allows to gang two, three or virtually unlimited quantity of servos together to increase output torque on rudder or to anywhere. If surface is large, one servo is never enough.
WHAT PROBLEMS ARE WE TRYING TO SOLVE?
There is the main problem of commonly used co-called Bell-Crank System, which uses ball-ended push rods and servo arms to connect servos and the bell-crank.
This problem is - adjusting bell-crank system. To have whole system work properly and to avoid servos to fight each other you have to make the length of each push rod absolutely the same. Technically it’s almost impossible so there is some difference always. We just cannot see this or measure it but it exists. And it’s also some loses of power.
There are some limits of the angle you can turn your rudder using bell-crank. It’s because of at some moment the rudder horn sets against the fuselage and it limits the angle of deflection. In order to increase the deflection it is impossible to keep enlarging the rudder horn size till infinity. Using pulley-pulley system you’ll have no limits of it. You can experiment with any size of deflection!
WHAT THE NEW APPROACH IS?
Our system is an absolutely new approach to solve the problems mentioned above.
First of all this system keeps the torque steady all the time regardless the angle of deflection.
It happens just because we use so called Timing Belt, which is commonly being used for millions of different purposes everywhere. You can find these kinds of belts almost in every machine: starting from printers, faxes and scanners on your table and up to the cars, motorcycles, elevators, transporters and etc, you name it.
By unknown reason it was used everywhere for tens of years except model aircrafts industry. But it’s not anymore. We have done it.
Timing Belt is actually just a tooth belt. It’s very flexible and very robust belt made of special rubber reinforced with glass fiber. This product of highest quality made in Germany. Obviously it speaks for itself.
There is no need to lubricate it, or to strain it. These belts work precisely without any creeping or play transferring gigantic forces. The only play you have is the one, which is in the servo gear. But there is unfortunately nothing we can do about it.
The tooth pulleys made of very strong and rigid fiberglass filled plastic. Each pulley can be installed on top of each other, letting you design practically any configuration of the system.
We currently designed three commonly used configurations. TBS-2 designed to gang TWO servos together. TBS-3 designed to gang THREE servos together. TBS-4 is ganging FOUR servos together. There is also TBS-1 (not shown) which just allows you to transfer the torque from the single servo to the bell-crank or the pulley. It allows you to transfer the force to the cable, which pulls the rudder through the same bell-crank so the bending moment, which is created by tightened cables, is not being transferred to the servo shaft. You can use it for smaller aircrafts. (Servos are not included!)
There is no fundamental difference between systems TBS-1, TBS-2, TBS-3 or TBS-4. The only difference is the size of the base made from aluminum and quantity of the pulleys and belts used. All parts are standardized. You can use standard size servos of any brand you wish. TBS system allows you to adjust it easily. For example if Hi-tech servos have 48 mm distance between mounting holes, at the same time standard Futaba servos have 50 mm between similar holes. The same servo tray (Base Plate) could be used for different brands. Servo mounting adapters have special slots so you can position the servos exactly where it is to be.
If you want to get full advantage from this new system, and it’s HUGE, one very important thing must be done. Some day you’ll have to reject bell-crank. You will have to place pulley on output shaft. If you place absolutely the same pulley at the bottom of the rudder and join them with regular cable, you’ll get this advantage. No more heavy and cumbersome cranks. The rudder deflection becomes unlimited.
In some aircraft designs TBS even allows you to make cables invisible. By the way, we are going to use this system in to our new ARF kit, which is coming very soon.
If you are not ready for this yet, it’s ok. We have bell-crank as well, which could be installed on top of output pulley. And you still have some advantages, which TBS system gives you. If you don’t want to use pulleys and belts, you can buy our SERVO TRAY set WITH BELL-CRANK and keep using ball-links and push-rods. Output pulley has two ball bearings as you can see at the pictures. You can also design your own system using TBS spare parts.
WHAT’S THE ADVANTAGE OF USING TBS SYSTEM?
First - you gain the power. You don’t lose energy to make servos to fight each other. You keep the same torque and angular velocity regardless the angle the rudder turned. If you wish it can be rotated 90 degrees or even 360!
Second - the adjustments are simple. Just install the pulleys on the servo shaft and sub trim it till tooth on the belt seats between proper teeth on the pulley.
And finally third – it’s just cheaper! It’s because we use very effective and at the same time simple tools to manufacture our products!Download TBS Manual (PDF File)