[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.31,0:00:01.75,Default,,0000,0000,0000,,The planetary gear set,
Dialogue: 0,0:00:01.75,0:00:02.72,Default,,0000,0000,0000,,also known as,
Dialogue: 0,0:00:02.72,0:00:04.26,Default,,0000,0000,0000,,the epicyclic gear train
Dialogue: 0,0:00:04.26,0:00:05.26,Default,,0000,0000,0000,,is one of the most
Dialogue: 0,0:00:05.26,0:00:06.47,Default,,0000,0000,0000,,important and interesting
Dialogue: 0,0:00:06.47,0:00:08.35,Default,,0000,0000,0000,,inventions in engineering.
Dialogue: 0,0:00:08.35,0:00:09.49,Default,,0000,0000,0000,,They are great speed \N
Dialogue: 0,0:00:09.49,0:00:10.81,Default,,0000,0000,0000,,variation mechanisms
Dialogue: 0,0:00:10.81,0:00:11.88,Default,,0000,0000,0000,,and are often used in
Dialogue: 0,0:00:11.88,0:00:13.81,Default,,0000,0000,0000,,automobiles as a vital part of
Dialogue: 0,0:00:13.81,0:00:15.23,Default,,0000,0000,0000,,automatic transmissions.
Dialogue: 0,0:00:18.58,0:00:19.97,Default,,0000,0000,0000,,Let's explore the secrets
Dialogue: 0,0:00:19.97,0:00:21.28,Default,,0000,0000,0000,,of the planetary gear set
Dialogue: 0,0:00:21.28,0:00:22.80,Default,,0000,0000,0000,,in this video!
Dialogue: 0,0:00:24.69,0:00:26.13,Default,,0000,0000,0000,,A planetary gear set
Dialogue: 0,0:00:26.13,0:00:28.03,Default,,0000,0000,0000,,has four main parts:
Dialogue: 0,0:00:28.48,0:00:29.94,Default,,0000,0000,0000,,the sun,
Dialogue: 0,0:00:30.37,0:00:31.88,Default,,0000,0000,0000,,planet gears,
Dialogue: 0,0:00:32.96,0:00:34.54,Default,,0000,0000,0000,,ring gear,
Dialogue: 0,0:00:35.54,0:00:37.14,Default,,0000,0000,0000,,and carrier.
Dialogue: 0,0:00:37.40,0:00:38.41,Default,,0000,0000,0000,,You can see that it
Dialogue: 0,0:00:38.41,0:00:40.53,Default,,0000,0000,0000,,sometimes rotates quickly,
Dialogue: 0,0:00:41.71,0:00:43.88,Default,,0000,0000,0000,,sometimes slowly,
Dialogue: 0,0:00:46.02,0:00:47.28,Default,,0000,0000,0000,,and sometimes
Dialogue: 0,0:00:47.28,0:00:48.87,Default,,0000,0000,0000,,even in reverse.
Dialogue: 0,0:00:50.20,0:00:52.49,Default,,0000,0000,0000,,But, how does this happen?
Dialogue: 0,0:00:52.49,0:00:53.47,Default,,0000,0000,0000,,You will be able
Dialogue: 0,0:00:53.47,0:00:54.51,Default,,0000,0000,0000,,to predict the motion\N
Dialogue: 0,0:00:54.51,0:00:55.90,Default,,0000,0000,0000,,of this gear set completely,
Dialogue: 0,0:00:55.90,0:00:56.84,Default,,0000,0000,0000,,if you understand
Dialogue: 0,0:00:56.84,0:00:58.47,Default,,0000,0000,0000,,one simple fact!
Dialogue: 0,0:00:59.10,0:01:00.32,Default,,0000,0000,0000,,When two gears
Dialogue: 0,0:01:00.32,0:01:01.52,Default,,0000,0000,0000,,are moving as shown,
Dialogue: 0,0:01:01.52,0:01:02.36,Default,,0000,0000,0000,,they should have
Dialogue: 0,0:01:02.36,0:01:03.36,Default,,0000,0000,0000,,the same speed
Dialogue: 0,0:01:03.36,0:01:05.01,Default,,0000,0000,0000,,at the interface.
Dialogue: 0,0:01:05.01,0:01:06.00,Default,,0000,0000,0000,,This means, that the
Dialogue: 0,0:01:06.00,0:01:07.50,Default,,0000,0000,0000,,speed of gear A,
Dialogue: 0,0:01:07.50,0:01:08.49,Default,,0000,0000,0000,,should be the same \N
Dialogue: 0,0:01:08.49,0:01:09.49,Default,,0000,0000,0000,,as gear B,
Dialogue: 0,0:01:09.49,0:01:11.52,Default,,0000,0000,0000,,at their mating point.
Dialogue: 0,0:01:17.15,0:01:18.05,Default,,0000,0000,0000,,The speed
Dialogue: 0,0:01:18.05,0:01:19.61,Default,,0000,0000,0000,,has to be the same
Dialogue: 0,0:01:19.61,0:01:20.61,Default,,0000,0000,0000,,otherwise,
Dialogue: 0,0:01:20.61,0:01:21.61,Default,,0000,0000,0000,,the gear teeth will penetrate
Dialogue: 0,0:01:21.61,0:01:22.99,Default,,0000,0000,0000,,each other as shown.
Dialogue: 0,0:01:22.99,0:01:25.81,Default,,0000,0000,0000,,That is an impossible condition.
Dialogue: 0,0:01:26.87,0:01:28.12,Default,,0000,0000,0000,,Just apply this fact
Dialogue: 0,0:01:28.12,0:01:29.63,Default,,0000,0000,0000,,to planetary gear sets,
Dialogue: 0,0:01:29.63,0:01:30.75,Default,,0000,0000,0000,,and you will be able
Dialogue: 0,0:01:30.75,0:01:31.76,Default,,0000,0000,0000,,to predict how
Dialogue: 0,0:01:31.76,0:01:33.84,Default,,0000,0000,0000,,speed variation is achieved.
Dialogue: 0,0:01:35.88,0:01:37.27,Default,,0000,0000,0000,,Assume that the ring gear
Dialogue: 0,0:01:37.27,0:01:38.44,Default,,0000,0000,0000,,is held stationary
Dialogue: 0,0:01:38.44,0:01:40.28,Default,,0000,0000,0000,,and we rotate the sun gear.
Dialogue: 0,0:01:43.93,0:01:45.17,Default,,0000,0000,0000,,Think of what happens
Dialogue: 0,0:01:45.17,0:01:46.83,Default,,0000,0000,0000,,to the planet gears!
Dialogue: 0,0:01:47.97,0:01:48.97,Default,,0000,0000,0000,,At point A,
Dialogue: 0,0:01:48.97,0:01:49.97,Default,,0000,0000,0000,,the planet gear
Dialogue: 0,0:01:49.97,0:01:51.75,Default,,0000,0000,0000,,should have a certain speed
Dialogue: 0,0:01:51.75,0:01:53.12,Default,,0000,0000,0000,,and at point B,
Dialogue: 0,0:01:53.12,0:01:54.34,Default,,0000,0000,0000,,the speed should be zero,\N
Dialogue: 0,0:01:54.34,0:01:55.34,Default,,0000,0000,0000,,as the ring gear
Dialogue: 0,0:01:55.34,0:01:56.96,Default,,0000,0000,0000,,is stationary.
Dialogue: 0,0:01:56.96,0:01:57.74,Default,,0000,0000,0000,,However,
Dialogue: 0,0:01:57.74,0:01:58.53,Default,,0000,0000,0000,,how are both
Dialogue: 0,0:01:58.53,0:01:59.51,Default,,0000,0000,0000,,of these conditions\N
Dialogue: 0,0:01:59.51,0:02:01.41,Default,,0000,0000,0000,,possible at the same time?
Dialogue: 0,0:02:01.74,0:02:03.75,Default,,0000,0000,0000,,There is only one way,
Dialogue: 0,0:02:03.75,0:02:04.83,Default,,0000,0000,0000,,the planet gear
Dialogue: 0,0:02:04.83,0:02:07.56,Default,,0000,0000,0000,,should spin as well as turn!
Dialogue: 0,0:02:07.56,0:02:08.84,Default,,0000,0000,0000,,The spinning will produce
Dialogue: 0,0:02:08.84,0:02:10.80,Default,,0000,0000,0000,,velocities in opposite [directions]
Dialogue: 0,0:02:10.80,0:02:12.28,Default,,0000,0000,0000,,at the top and bottom points,
Dialogue: 0,0:02:12.28,0:02:13.79,Default,,0000,0000,0000,,as shown,
Dialogue: 0,0:02:13.79,0:02:15.03,Default,,0000,0000,0000,,whereas, the turning
Dialogue: 0,0:02:15.03,0:02:17.39,Default,,0000,0000,0000,,produces unidirectional velocities.
Dialogue: 0,0:02:18.85,0:02:19.87,Default,,0000,0000,0000,,At the top,
Dialogue: 0,0:02:19.87,0:02:21.60,Default,,0000,0000,0000,,the spinning and turning velocities
Dialogue: 0,0:02:21.60,0:02:23.45,Default,,0000,0000,0000,,are in opposite directions,
Dialogue: 0,0:02:23.45,0:02:24.45,Default,,0000,0000,0000,,so the velocity of
Dialogue: 0,0:02:24.45,0:02:25.85,Default,,0000,0000,0000,,point B is zero.
Dialogue: 0,0:02:25.85,0:02:27.08,Default,,0000,0000,0000,,At the bottom,
Dialogue: 0,0:02:27.08,0:02:29.73,Default,,0000,0000,0000,,they get added up.
Dialogue: 0,0:02:29.73,0:02:30.87,Default,,0000,0000,0000,,In short,
Dialogue: 0,0:02:30.87,0:02:31.98,Default,,0000,0000,0000,,the Planet gears
Dialogue: 0,0:02:31.98,0:02:33.19,Default,,0000,0000,0000,,are forced to turn
Dialogue: 0,0:02:33.19,0:02:34.37,Default,,0000,0000,0000,,in order to satisfy
Dialogue: 0,0:02:34.37,0:02:35.73,Default,,0000,0000,0000,,the condition of velocity.
Dialogue: 0,0:02:35.73,0:02:37.51,Default,,0000,0000,0000,,As the carrier is attached
Dialogue: 0,0:02:37.51,0:02:38.97,Default,,0000,0000,0000,,to the planet gear
Dialogue: 0,0:02:38.97,0:02:40.24,Default,,0000,0000,0000,,it will turn along
Dialogue: 0,0:02:40.24,0:02:42.39,Default,,0000,0000,0000,,with the planet gears.
Dialogue: 0,0:02:45.85,0:02:48.37,Default,,0000,0000,0000,,Now let's see what happens when the sun gear is held stationary and the ring gear is rotated
Dialogue: 0,0:02:50.40,0:02:55.64,Default,,0000,0000,0000,,This is the exact opposite to the previous case at the inner point of the planet gear
Dialogue: 0,0:02:55.64,0:03:01.04,Default,,0000,0000,0000,,the Velocity should be zero and the outer points should have the speed of the ring gear.
Dialogue: 0,0:03:01.04,0:03:06.70,Default,,0000,0000,0000,,in This case the planetary Spin will reverse in order to satisfy the speed conditions
Dialogue: 0,0:03:08.100,0:03:11.74,Default,,0000,0000,0000,,However this case has one more difference
Dialogue: 0,0:03:12.29,0:03:17.55,Default,,0000,0000,0000,,The speed of point B. Will be higher than [the] speed of point A in the previous case
Dialogue: 0,0:03:18.21,0:03:21.77,Default,,0000,0000,0000,,This is obvious as the ring gear radius is higher
Dialogue: 0,0:03:26.16,0:03:33.76,Default,,0000,0000,0000,,This will make the planet gear spin and turn at a higher speed thus the carrier will turn at a higher speed
Dialogue: 0,0:03:36.57,0:03:40.37,Default,,0000,0000,0000,,Let's now explore this reverse mechanism of Planet Gears
Dialogue: 0,0:03:42.58,0:03:46.69,Default,,0000,0000,0000,,For this what you have to do is just arrest the motion of the carrier
Dialogue: 0,0:03:47.100,0:03:53.15,Default,,0000,0000,0000,,This means the Planet gears are not allowed to turn and can only spin
Dialogue: 0,0:03:55.02,0:03:58.44,Default,,0000,0000,0000,,This Spin will be opposite to the rotation of the sun gear
Dialogue: 0,0:03:59.63,0:04:04.28,Default,,0000,0000,0000,,This spinning Planet Gear will make the ring gear rotate in the same Direction
Dialogue: 0,0:04:04.62,0:04:12.02,Default,,0000,0000,0000,,In short the direction of rotation of the ring Gear will be the opposite to the sun gear thus we will get the reverse gear
Dialogue: 0,0:04:15.37,0:04:22.63,Default,,0000,0000,0000,,Here you can note that in order to achieve different speeds the input must be given to different parts of the planetary gearset
Dialogue: 0,0:04:22.63,0:04:25.70,Default,,0000,0000,0000,,This is practically difficult in an actual mechanism
Dialogue: 0,0:04:26.53,0:04:29.08,Default,,0000,0000,0000,,in an automatic transmission [to] achieve this
Dialogue: 0,0:04:29.08,0:04:35.21,Default,,0000,0000,0000,,Three planetary gear sets are connected in series as shown with coaxial Shafts
Dialogue: 0,0:04:35.70,0:04:41.82,Default,,0000,0000,0000,,To understand how this arrangement effectively transfers the input rotation to different parts of the planetary gearset
Dialogue: 0,0:04:41.82,0:04:44.66,Default,,0000,0000,0000,,Watch our video on automatic transmission
Dialogue: 0,0:04:45.61,0:04:49.61,Default,,0000,0000,0000,,Your support on patreon.com is greatly appreciated to make our educational service sustainable. Thank you