Our customer would like to know the slewing bearing and pinion’s load capacity, the maximum allowable torque, the catastrophic load point, and the life calculation.
🔎 Can you recognize what the conflicting point is?
👇 Information customer provided:
Bearing: A170308
Pinion: A170310
Continuous torque: 30,000 ft-lbs
Relief torque: 42,000 ft-lbs
Speed: 0.025 rpm
Hanging Weight: 23,000 lb
👇 Calculation UIPI offered:
Bearing: A170308
Life: L10=500,000(R)
Max axial load: Fa=3650KN; (Mq=0), Max moment: Mq=965KNM; (Fa=0)
Catastrophic load: F=22637KN
Teeth max allowable torque: M=155KNM
Teeth catastrophic torque: Md=643KNM
Pinion: A170310
Teeth max allowable torque: Mr=15KNM=11073.375ft-lbs
Teeth catastrophic torque: Md=655KNM=483537.375ft-lbs
Yes, our calculation (The teeth max allowable torque: M=15KNM=11073.375ft-lbs) is much lower than the customer-provided number (Continuous torque: 30,000 ft-lbs)
The customer got confused and asked, “Would the 15KNM be a typo?”
We confirmed that the teeth max allowable torque is indeed 15KNm by our calculation for the pinion.
But, as we mentioned before, we doubt that torque 30,000 ft-lbs is not the continuous working torque, it may be the max output torque for the customer's gearbox/motor.
If 30,000 ft-lbs is indeed the continuous working torque, based on calculation, the working torque between 11073.375ft-lbs and 483537.375ft-lbs will reduce the pinion's life, which we don't recommend the pinion working in such conditions.
This slewing bearing application is a large tank, and an arm is attached to the bearing at the center to keep all the water in the tank moving - hence the very low speed, low weight, and high torque.
And we found another misunderstanding: The load on the bearing teeth and the pinion teeth should be the same, and the torque is related to the radius and should be different on the bearing and pinion, which but customer thought would be the same.
The maximum torque the pinion can undertake is 26KNm(19,200 ft-lbs). We think 30,000 ft-lbs of torque may not be on the pinion, but on the bearing. Because if it is on the bearing, it works without any questions. If it is on the pinion, the bearing will take a torque that much higher than 30,000 ft-lbs.
After the customer’s calculation, The maximum force coming from the planetary gearbox is 18,659lbs, which puts the torque load on the pinion at around 5,500ft-lbs.
And we confirm that the torque 5,500ft-lbs is good for the pinion to work.
This is a glimpse of our daily communication with our customers. 🤝