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Automotive Transmissions and Drive Trains
Published in Don M. Pirro, Martin Webster, Ekkehard Daschner, Lubrication Fundamentals, 2017
Don M. Pirro, Martin Webster, Ekkehard Daschner
Sliding element transmissions are typically used in only low speed applications, such as tractors. In this application, the clutch must be disengaged and the vehicle must be at a complete stop before the gears can be engaged or the gear ratio changed. For other applications, syncromesh or synchronized transmissions are used. In this type of transmission, all gears are always in mesh, except the reverse gear. One of each pair of gears is free to revolve on its shaft unless locked to it by a clutching mechanism called a synchronizer as shown in Figure 11.2. The synchronizer, which is keyed or splined to the shaft, consists of a friction clutch and a dog clutch. As the shift fork moves the synchronizer toward the gear, the friction cones make contact first to bring the shaft to the same rotational speed as the gear. The outer rim of the clutch gear then slides over its hub, causing a set of internal teeth to engage with a set of teeth (dogs) on the side of the gear. This then provides a positive mechanical connection between the gear and shaft.
Layshaft gearboxes
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
This takes from its splined end the drive from the clutch-driven member or centre plate. Supported by a rolling bearing in the front end of the gearbox casing and a spigot bearing in the engine flywheel, it carries the constant-mesh pinion for driving the layshaft. The pinion is also equipped with dog clutch teeth providing direct connection with the mainshaft dog clutch when fourth speed is engaged. This principle of utilizing a direct-drive top gear was first established by another famous French automotive pioneer, Louis Renault, in 1899. A spigot bearing is contained within the constant-mesh pinion to support the nose of the mainshaft.
Automated Lathes
Published in Helmi Youssef, Hassan El-Hofy, Traditional Machining Technology, 2020
Figure 8.21 shows a detailed drawing of the dog clutch (single-revolution). This type of clutch is not recommended for a rotational speed that exceeds 200 rpm. It operates in the following manner: The gear (1) is rotated only one revolution by the auxiliary shaft (2) and is then automatically disengaged.Long jaws are provided at the end of the gear (1) and clutch members (B), so that they do not disengage when a member is shifted to engage the jaws at the right end.In the disengaged condition, the clutch member is retained by the lock pin (D).If the lock pin is withdrawn from its slot, the spring forces the clutch member to the right and engages the disk (3). The gear starts rotating through the clutch members.The pin slides along the external surface of a clutch member until it drops into the recess of a beveled surface, which forces the clutch member, upon further rotation, toward the left to disengage the gear from the rotating disk after one complete revolution.The lock pins (D and A) are backed by their springs.
An Investigation into the Influence of Viscosity on Gear Churning Losses by Considering the Effective Immersion Depth
Published in Tribology Transactions, 2023
Joseph F. Shore, Anant S. Kolekar, Ning Ren, Amir Kadiric
This rig consists of an electric motor with a step-up belt drive, which drives the test gear in its housing. The gear shaft is coupled to the driven pulley shaft with a manually disconnected dog clutch. The nylon test spur gear, with geometrical parameters listed in Table 1, is mounted on the gear shaft and rotates in the oil sump. The gear is situated in a cylindrical housing which has an internal diameter of 168 mm and width of 80 mm. This is a relatively closely fitting housing chosen to mimic automotive transmissions [1]. An optical encoder is mounted on the gear shaft to measure the rotational speed of the gear. As shown in Fig. 1a, the gear shaft is cantilevered on oil lubricated bearings which are external to the test housing. These bearings and their seals therefore do not interact with the oil in the gear housing. Sealed polycarbonate windows on either side of the gear housing were used to observe oil flow during the tests.