Mechanical Engineering Drawing MENG 204
Summer Semester 2015By:
Dr. Ghassan Mousa
Fasteners & shafts
Thread standards & definition
• d: major diameter
• p: pitch
• l: lead
• Multiple threads
• Die for external threading.https://www.youtube.com/watch?v=gVcwjjBAT4Q
• Tab for internal threading
Fig. 8.1 Terminology of screw threads
http://www.gizmology.net/nutsbolts.htm
Threaded fastenersUsed to non-permanently join one or more objectstogether.
http://www.walter-tools.com/en-gb/tools/standard_products/threading/overview/hss_tap/eco_ht/Pages/default.aspx
Types
Three types of threaded fastener. (a) Bolt and nut; (c) Cap screw; (c) stud.
Metric thread
• Thread angle is 60˚
• M8 × 1.25
Imperial thread
• Thread angle is 60˚
• 3/8 – 24 UNF
Table 8-1 Geometrical data for Standard Bolts (SI)
Power screw
Trapezoidal thread
• Thread angle is 30˚
• Tr 36 X 10
Buttress Thread
• Thread angle is 30˚
• S 40 X 7
Loading Direction
Strength
Bolts in axial loading fail at the:
• Fillet under the head.
• Thread runout.
• 1st thread engaged in the nut.
Table 8-11 Material properties of steel bolts
• Setscrew
• washer
• Nuts• Slotted nut jam nut
• Prevailing torque locknut
Design (Configuration)
Design (Head Style)
Design (Drive Type)
Thread dimension
Threaded Fasteners Preferred
Sizes (Length):
• 2, 3, 4, 5, 6, 8, 10
• 12, 16, 20, 25, 30
• 35-60, 65, 70, 80
• 90-140, 150, 160, 180, 200
Shafts
• Used to transmit power (torque).
• The shorter the better.
• Load carrying components should be placed near the bearing.
• Means of transmitting power through:• Gears• Belts• Chains
• Torque is transmitted by using keys
• Axial force is supported by using Pins
Stepped shaft
Retaining rings
External ringE ring
Keys
Tapered keyGib head tapered key
Woodruff key
Pins
Spring pin
Dowel pinHairpin cotter
Cotter pin Tapered pin