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Integration System for Fixture Layout Design
Published in Awais Ahmad Khan, Emad Abouel Nasr, Abdulrahman Al-Ahmari, Syed Hammad Mian, Integrated Process & Fixture Planning, 2018
Awais Ahmad Khan, Emad Abouel Nasr, Abdulrahman Al-Ahmari, Syed Hammad Mian
The T-slot system uses a series of precisely machined base plates, mounting blocks, and other elements having machined and ground T slots. The slots are used to mount and attach the additional accessories. The major advantages with these base plates are adaptability, strength, and ease of positioning the component. The T slots do not require components to be located at fixed points and so permit more movement of the components on the base plates. Therefore, the parts are generally easier to fixture when the work-holding elements are located in T slots. The major disadvantage of the T slot system is in its repeatability from one tool to the next because of the absence of rigid reference points. On the other hand, the dowel pin system uses a grid pattern of holes to locate and mount the other accessories. The principle advantage of the dowel pin system is in the automatic positioning of the components from one tool to the next. If a tool must be built more than once, the components are faster and easier to locate with the dowel pins. The overall stiffness of the dowel pin modular fixture system is higher than the T slot system. Moreover, the dowel pin system is easy to manufacture and provides the precise location of the part [13].
The reciprocating piston petrol engine
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
The once traditional method of attachment was to key the timing wheel on a reduced-diameter extension of the camshaft, endwise retention being effected by a central clamping nut. To prevent relative rotation between the clamped parts a ‘Woodruff’ key was used, this being close fitting only on the sides of its keyway and self-aligning by virtue of its semicircular form (Figure 1.111a). In modern practice, the function of the Woodruff key is generally replaced by that of an off-centre dowel pin (Figure 1.111b). The dowel pin is simply a plain cylindrical pin that is made close fitting in corresponding holes in the timing wheel and the end face of the camshaft, these two members being spigotted together for radial location. Their endwise clamping is effected by a central bolt.
Centrifugal Pumps
Published in Don Renner, Hands-On Water/Wastewater Equipment Maintenance, 2017
12.52 The manufacturers of most double-suction pumps place a set of dowel pins in the bottom half or base of the casing. The dowel pins match a set of holes in the top half of the casing and provide proper alignment between the two halves when they are assembled. The dowel pins are usually set at opposite corners of the casing so the pump can be assembled in only one position.
Developing specifications for precast concrete highway pavements
Published in International Journal of Pavement Engineering, 2022
Daniel Offenbacker, Douglas Cleary, Ayman Ali, Yusuf Mehta
Load transfer systems involve the use of slots on one or both sides of the joint and are located at the top or bottom of the PCP panel. The slots are usually narrow and are open for the full or a partial length of the dowel. Several studies on PCP systems provide a summary of the currently used load transfer systems including the bottom slot, narrow mouth, teardrop, and sliding dowels (Tayabji et al., 2012, Tayabji and Brink, 2015a, The Fort Miller Company Inc., 2015, NPCA, 2018b). Bottom-slot load transfer system: Incorporates dowel slots at the bottom of the slab. In a repair situation, dowel holes are drilled into the existing pavement and the dowel bars are epoxied into the holes. The repair panel is then lifted into place over the dowels and a flowable grout is used to fill the dowel slot. The bottom panel dowel slots are shown in Figure 2(a).Narrow-mouth dowel systems: Developed as an alternative to a full dowel bar retrofit that requires slots on both sides of the joint. At the surface, the slots are about 1 inch wide and spread to about 3 inches wide and within an inch below the panel mid-height. The narrow width at the surface allows for temporary traffic prior to grouting the dowels. With this type of dowel system, the dowel bars are placed in a longer dowel slot (14 to 16-inches long). Once the panel is positioned, the dowel is slid into predrilled holes in the adjoining panel. Figure 2(b) shows a modification developed by the Illinois DOT system that includes a widened section near the joint that allows for sliding and rotating the dowel by hand and improving epoxy adhesion to the bar. The dovetail shape of this dowel system is beneficial because it provide resistance to dowel pop-out, however, this system must be field installed and cannot be cast-in-place. Therefore, the performance of this system is also dependent on the encasement grout used to secure the dowel.Teardrop dowel system: Has been used rather than the triangular shape for better installation (Figure 2(c)).Sliding dowel system: Has been recently developed and incorporated in some state DOT systems with only a partially open narrow slot (Figure 2(d)). Based on the SME responses, these are recommended due to their simple use and increased efficiency.