Precautions when using our products

  1. Using the R/C servo properly
    1. There is no rated torque specified for the R/C servo. Only the total starting torque of the servo is in the spec sheet. This is probably because it was originally developed for aviation applications where the steering time of an aircraft is short period, even the total of powered usage time for an acrobatic aircraft is not so long. Accordingly, the amount of heat created by the current to the DC motor coil is also low so there are no problems even when used under such conditions with near usage of the starting torque. For example, the starting torque of our SSPS-105 is 380 kg-cm. Under some operating conditions such as the load torque is needed continuously, only 20 kg-cm can be used, because of absolute maximum heat temperature of the motor coil must be less than 120 deg. C. This depends on the environment temperature and cooling fan.
    2. Damage to a R/C servo can be caused by extremely high impact, such as a plane crash, or the generation of heat. It would not be an exaggeration to say that the latter accounts for more than 99% is the motor over heat damage.
    3. The proper use of the R/C servo is the secret to not causing heat damage. The following is a brief explanation of the bad conditions that can cause heat damage and steps that can be taken to avoid it.
      1. When a DC motor is started, approximately only the motor coil resistance limits the input power current. This is called the starting current. After this, the motor rotes and generates the self-generative voltage and reduce the input power current. Therefore, the average input current depends on motor running as rotating timing. The RC servo does run a few second period. This means the RC servo uses almost starting condition current. In actual tests we have conducted, we sent a 3 cycle forward and reverse rotate direction signal at 1-second intervals during the no-gear train test with various kinds of motors and this resulted in burn damage within approximately 30 minutes for all of them with no-load.
      2. When used together with a gyroscope, the servo input pulse included jitter without response tuning and/or noise filtering condition as shown follow. The jitter causes the motor hardly turns repeating back and force as one-quarter reciprocal rotation. This causes burning that burned out one pole in the motor coil.
        Filter for gyroscope
      3. When used for applications such as the throttle on large engines where the horn receives a lot of vibration, when the servo output shaft has vibrated even an extremely small amount of rotating and tries to return, the servo amp will operate and ultimately cause electrode burning. Under these conditions, introduce a mechanical filter and damper to reduce the inertia of the linkage mechanism to the servo. In the case of the operation of direction control on engines for large blimps, the weight of the engine itself will be loaded. Appropriate measures of the load will be required.
      4. When using the unit for tilting (moving in a longitudinal direction) a large video camera, the center of gravity of the camera will move according the angle, applied to the servo and causing electrode burning. Align with the rotational center of gravity of the camera. Constantly applying force to support it in that condition is called hold. Consider the R/C servo hold force to be less than 1/20 that of the starting torque.
      5. Refer to Fig.of follow, when the unit is used for a switching valve, such as on hydraulic equipment. This figure shows a mechanism comprised of a cam and cam follower. The slight variation of the servo output shaft at the attainment point of each (a) and (b) gives (R1) (R2) at each attainment point so that there is nothing applied to the servo. The application of force to the servo is only during the movement from point (a) to point (b). If this movement time is short, this will be the ideal usage as the power used is near that of the starting torque.
        cum follower
        This is also a mechanism comprised of a cam and cam follower. The line of action of the gravity matches the servo output shaft line so there is absolutely no load on the servo at both attainment points (a) and (b). Under this condition as well, extensive torque can be extracted. However, since there is a load between the cam points, it cannot be stopped for more than 10 seconds. If current is sent to the motor in the locked position, burning will occur in 30 seconds while highly durable motors may last up to one minute.
      6. If electricity flows while in the motor locked position as follow, the current will flow only to coil (a) and (c). Heat will concentrate to here one of pole and cause the motor to burn out.
        coil connection
      7. In Fig. of follow is an example of the concept when the weight is lifted up to (Pb) from the start point of the lower support (Pa). Looseness is taken at starting point (Pa) and when under any condition the horn rotation position system did not hold, an excessive load is applied.

        The first to consider is preventing the burning of the electrodes. Let's take a look at conditions for the upper support point (Pb). The line of action at upper support point (Pb) matches the shaft line of the horn. At this time, the rotational force, i.e. torque, does not function at the shaft (horn). If the position is changed even slightly, only an extremely small load torque will function. Accordingly, only an extremely small amount of current will flow to the DC motor so the amount of heat generated is smaller than the amount of heat dissipated, so a rise in temperature does not occur and there is no damage.
        wire up
      8. Above we presented summaries of examples of how to use R/C servo motors. Use these same concepts for link mechanisms. If used properly, the R/C servo offers a power-to-weight ratio that cannot be found in other position control servo systems.