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Pratt Burnerd 3-Jaw Constant Grip Power Chucks

MADE IN USA

Constant Grip High Speed Standard and King Bore Thru-Hole Power Chucks Sizes 6″ Thru 24″

  • MADE IN USA

  • One Year Warranty

  • High RPM – up to 6000

  • Constant Grip, internally counter-balanced design that reduces grip loss from centrifugal force of the jaws at high RPM.

  • Easy Retrofit on most all existing NC and CNC lathes utilizing the same drawtube and actuating cylinder including Japanese types.

  • Accurate – repeatability of ± .0005″

  • 3-Point Adjusting Feature in the chuck body permits indicating in to zero. Increase Soft Jaw Life by using adjustment feature. Reduce or eliminate re-boring of Soft Jaws.

  • Doubles as collet chuck as master jaws have keyed radius in front that accept standard W & S collet pads. Eliminate time wasted on switching over to collet chuck.

  • Large Thru-Hole Capacity

  • Utilize existing top tooling by selecting style of master jaws from 1.5 x 60, 1/16″ x 90, Am. Std. Acme, Am. Std Tongue & Groove and Square Serrationsor substitute mono block jaws. Sets can be mixed styles.

  • Also available in 2-jaw style.

  • Chuck sizes available 6″, 8″, 10″, 12″, 15″,18″, 20″ and 24″ diameters.

STANDARD BORE CHOICES
Chuck Size
Mount Direct and Indirect
RPM
Model Number
Jaw Stroke
Sleeve Stroke
Thru Hole
Collet Pad Bar Capacity
Tooling Hole Size
Operating Force lbs/f
Grip Force lbs/f
Wt (lbs)
6.5"
A2-4(I)
6000
9151-217__
.140"
.630"
1.65"
1.5"
5/16" UNC
3600
9900
31
6.5"
A2-5(D)
6000
9151-317__
.140"
.630"
1.65"
1.5"
5/16" UNC
3600
9900
31
6.5"
A2-6(I)
6000
9151-417__
.140"
.630"
1.65"
1.5"
5/16" UNC
3600
9900
31
8.25"
A2-5(I)
5500
9151-321__
.140"
.630"
2.05"
2.0"
5/16" UNC
6200
15000
53
8.25"
A2-6(D)
5500
9151-421__
.140Z
.630"
2.05"
2.0"
5/16" UNC
6200
15000
53
8.25"
A2-8(I)
5500
9151-521__
.140"
.630"
2.05"
2.0"
5/16" UNC
6200
15000
53
10.0"
A2-6(I)
5000
9151-426__
.160"
.730"
2.56"
2.5"
3/8" UNC
7200
19800
82
10.0"
A2-8(D)
5000
9151-526__
.160"
.730"
2.56"
2.5"
3/8" UNC
7200
19800
82
12.0"
A2-8(I)
4200
9151-531__
.160"
.730"
3.54"
3.0"
3/8" UNC
9900
27000
150
12.0"
A2-11(D)
4200
9151-631__
.160"
.730"
3.54"
3.0"
3/8" UNC
9900
27000
150
15.0"
A2-8(I)
3000
9151-538__
.200"
.790"
4.92"
4.5"
3/8" UNC
13500
31500
280
15.0"
A2-11(D)
3000
9151-638__
.200"
.790"
4.92"
4.5"
3/8" UNC
13500
31500
280
18.0"
A2-8(I)
2500
9151-546__
.236"
.984"
5.59"
5.5"
1/2" UNC
15500
38250
375
18.0"
A2-11(I)
2500
9151-646__
.236"
.984"
5.59"
5.5"
1/2" UNC
15500
38250
375
20.0"
A2-11(I)
2500
9151-650__
.236"
.984"
5.59"
5.5"
1/2" UNC
15500
38250
550
24.0"
A2-11(I)
1800
9151-660__
.315"
.984"
6.299"
6.25"
1/2" UNC
20700
38250
760
24.0"
A2-15(D)
1800
9151-760__
.315"
.984"
6.299"
6.25"
1/2" UNC
20700
38250
760
KING BORE CHOICES
Chuck Size
Mount direct and Indirect
RPM
Model Number
Jaw Stroke
Sleeve Stroke
Thru Hole
Collet Pad Capacity
Tooling Hole Size
Oper. Force lbs/f
Grip Force lbs/f
Wt. lbs.
7.0"
A2-5(D)
7000
9161-318__
.140"
.630"
2.20"
2.0"
5/16" UNC
4500
13000
37
8.25"
A2-6(D)
5500
9161-421__
.140"
.630"
2.59"
2.5"
5/16" UNC
5400
15000
53
10.43"
A2-6(I)
5000
9161-426__
.160"
.730"
3.03"
3.0"
3/8" UNC
7200
19800
82
10.43"
A2-8(D)
5000
9161-526__
.160"
.730"
3.03"
3.0"
3/8" UNC
7200
19800
82
12.40"
A2-8(I)
4200
9161-531__
.160"
.730"
4.05"
4.0"
3/8" UNC
9900
27000
183
12.40"
A2-8(D)
4200
9161-531__
.160"
.730"
4.05"
4.0"
3/8" UNC
9900
27000
183

Insert last two digits for Master Jaw type...Example 9151-21723...Indicates 1.5mm x 60°: Master Jaw Required
Use 23 for 1.5mm x 60° Japanese type.** Use 07 for Am. Std Tongue & Groove. Use 10 for 1/16 X 90° Serrations.***
Use 26 for Acme Serration. Use 27 for Square Serration.
NOTE: 18, 20 & 24 dia. chucks require separate collet pad master jaws: 18-#8130-46696, 20-#8130-50696 & 24-#8130-61696.
**3mm on 20 and 24 dia. chucks ***3/32 x 90° on 20 and 24 chucks

PRATATLAS 3-DRAW CONSTANTGRIP STANDARD BORE PWRCHKS TECHSPEC.png
TECHNICAL SPECIFICTIONS
Chuck Size
A
B
C
D
F
Max
Min
6-A4
6.5
4.685
4.803
3.25
0.787
2.126
1.339
6-A5
6.5
4.842
4.96
4.125
0.787
2.126
1.339
6-A6
6.5
5.078
5.196
5.25
0.787
2.126
1.339
8-A5
8.25
5.119
5.275
4.125
1
2.637
1.733
8-A6
8.25
5.354
5.51
5.25
1
2.637
1.733
8-A8
8.25
5.705
5.862
6.75
1
2.637
1.733
10-A6
10
5.511
5.669
5.25
1.181
3.268
2.087
10-A8
10
5.905
6.063
6.75
1.181
3.268
2.087
12-A8
12
6.614
6.771
6.75
1.181
4.291
2.362
12-A11
12
6.614
6.771
9.25
1.181
4.291
2.362
15-A8
15
6.929
7.086
6.75
1.693
5
3.228
15-A11
15
6.929
7.086
9.25
1.693
5
3.228
18-A8
18
7.72
7.78
6.75
1.693
6.772
4.527
18-A11
18
7.72
7.78
9.25
1.693
6.772
4.527
20-A11
19.7
7.362
7.499
9.25
2.362
8.09
5.059
24-A11
24
7.56
7.72
9.25
2.362
10.09
5.77
24-A15
24
7.56
7.72
13
2.362
10.09
5.77
ADDITIONAL TECHNICAL SPECIFICTIONS
Chuck Size
G
H
J
K
Min
Max
S
W
6-A4
M10x25(6)
M10x25
5?16 UNFx1?2
2.99
0.94
1.57
0.475
1.22
6-A5
M10x130(3)
M10x25
5?16 UNFx1?2
2.99
1.1
1.73
0.475
1.22
6-A6
M12x30(6)
M10x25
5?16 UNFx1?2
2.99
1.5
2.13
0.475
1.22
8-A5
M10x30(6)
M12x35
3?8 UNFx3?4
3.94
0.98
1.61
0.551
1.57
8-A6
M12x130(3)
M12x35
3?8 UNFx3?4
3.94
1.19
1.81
0.551
1.57
8-A8
M16x30(6)
M12x35
3?8 UNFx3?4
3.94
2.02
2.65
0.551
1.57
10-A6
M12x35(6)
M12x35
1?2 UNFx3?4
4.53
1.02
1.75
0.63
1.57
10-A8
M16x150(3)
M12x35
1?2 UNFx3?4
4.53
1.41
2.15
0.63
1.57
12-A8
M16x40(6)
M14x45
1?2 UNFx3?4
5.71
1.3
2.03
0.71
1.81
12-A11
M20x160(3)
M14x45
1?2 UNFx3?4
5.71
1.3
2.03
0.71
1.81
15-A8
M16x35(6)
M20x55
1?2 UNFx3?4
473/789
1.38
2.16
0.866
2.36
15-A11
M20x180(6)
M20x55
1?2 UNFx3?4
473/789
1.38
2.36
0.866
2.36
18-A8
M16x40(6)
M20x55
1?2 UNFx3?4
433/630
1.38
2.36
0.984
2.36
18-A11
M20x35(6)
M20x55
1?2 UNFx3?4
433/630
1.38
2.36
0.984
2.36
20-A11
M20x45(6)
M20x35
1?2 UNFx3?4
705/994
1.38
236
0.984
2.36
24-A11
M20x45(6)
M20x35
1?2 UNFx3?4
***
1.57
2.56
0.984
2.36
24-A15
7/8-9x8(6)
M20x35
1?2 UNFx3?4
***
1.57
2.56
0.984
2.36

(T) Draw Tube Thread Blank
1. Dimensions listed are with 1.5 x 60° master jaws. Some dimensions will vary using other Master Jaw types such as Acme, 1/16" x 90° or Am. Std. Tongue & Groove.
2. Chuck is at mid stroke with master jaws flush with the body O.D.
3. UNC mounting bolts available upon request.
4. Standard master jaw serration for 20 and 24 inch chucks are 3mm x 60°.
***9.45"/13"/16.53"/20.08"

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