5-26
momentary maximum torque increases, and as the temperature rises the Servomotor’s momentary
maximum torque decreases. When the normal temperature of 20
°
C and -10
°
C are compared, the
momentary maximum torque increases by approximately 4%. Conversely, when the magnet warms
up to 80
°
C from the normal temperature of 20
°
C, the momentary maximum torque decreases by
approximately 8%.
•
Generally, in a mechanical system, when the temperature drops the friction torque increases and the
load torque becomes larger. For that reason, overloading may occur at low temperatures. In particu-
lar, in systems which use deceleration devices, the load torque at low temperatures may be nearly
twice the load torque at normal temperatures. Check with a monitor (using a torque command) to see
whether overloading is occurring at low temperatures, and how much the load torque is. Likewise,
check to see whether there abnormal Servomotor overheating or alarms are occurring at high tem-
peratures.
•
An increase in load friction torque increases the apparent load inertia. Therefore, even if the Servo
Driver parameters are adjusted at a normal temperature, there may not be optimal operation at low
temperatures. Check to see whether there is optimal operation at low temperatures too.
5-2-4 Allowable Loads on Servomotor Shafts
The allowable loads on Servomotor shafts are shown in the following table. Operate the Servomotor at
no more than the allowable radial and thrust loads. At the time of assembly, assemble the Servomotor at
no more than the momentary maximum radial and thrust loads (static pressure).
Servomotor
Momentary
allowable radial
load (static
pressure)
Momentary
allowable thrust
load (static
pressure)
Allowable radial
load
Allowable thrust
load
N
N
N
N
R88M-UE10030
-S1
186
127
78
54
R88M-UE20030
-S1
490
176
245
74
R88M-UE30030
-S1
490
176
245
74
R88M-UE40030
-S1
490
176
245
74
R88M-UE75030
-S1
735
392
392
147
Note 1. The allowable loads are the same for motors with brakes.
Note 2. The allowable radial load is the value at a point 5 mm from the end of the shaft.
Radial load
Thrust load
5 mm
Note 3. The allowable radial and thrust loads are values determined with a service life of 20,000 hours
taken as a criteria.
Note 4. The service life of bearing grease is 20,000 hours at a Servomotor ambient temperature of
40
°
C, and under the rated operating conditions.
Note 5. Absolutely do not impact the Servomotor or the output shaft by striking them with an imple-
ment such as a hammer. Doing so will damage the Servomotor and encoder bearings.
Specifications
Chapter 5
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