Assembly Drawings 291
dharm
d:\N-Design\Des18-2.pm5
R30^32
(^35) M12
R15
(^12518)
25
f 40
30
150
6
10 1
100
36
f^30
M15
18
R125
f 18
150
KEYWAY,
5 × 2.5
18
f^28 f^15 f^80
3
35
3
32
M12
(^6318)
5
35
f (^15) R15
60°
180
f^30
2
12
(^835)
SLOPE,
1:100
5
5
KEYWAY, 5×2.5
M15f^25
12 20
8
M15
2 15
f^32 M15
4
132
60
Sl. No. Name Matl. Qty.
1 2 3 4 5 6 7 8
Body
Centre
Hand wheel
Screw
Screw
Washer
Nut
Key
CI
Case hardened
alloy steel
Cast steel
MS
MS
MS
MS
MS
1 1 1 1 1 1 1
Parts list
Fig. 18.19 Milling machine tail-stock
18.3.7 Revolving Centre
When long bars are machined on a lathe, they are suppported on two centres. one of which is
called a live centre and the other, a dead centre, fixed in the tail-stock. The live centre fits into the
main spindle and revolves with the work it supports. Because of the relative motion between the
work piece and the dead centre in the tail-stock barrel, over-heating and wear of the centre takes
place in the long run. To eliminate this, the dead centre is replaced with a live or anti-friction
bearing centre, which revolves with the work like a live centre.
Figure 18.20 shows the details of a revolving centre using antifriction bearings. The radial
bearing 6 and thrust bearing 7 used in the design are meant for resisting the possible radial and
axial loads respectively. The sleeve 4 is press fitted in the barrel 1 to provide end support to the
