Pratt Burnerd/Atlas 3-Jaw Constant Grip Thru-Hole Power Chucks

Pratt Burnerd/Atlas
3-Jaw Constant Grip Power Chucks

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

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

Chuck Size	Mount (D)Direct (I)Indirect	RPM	Model No.*	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	3,600	9,900	31
6.5"	A2-5(D)	6000	9151-317__	.140"	.630"	1.65"	1.5"	5/16" UNC	3,600	9,900	31
6.5"	A2-6(I)	6000	9151-417__	.140"	.630"	1.65"	1.5"	5/16" UNC	3,600	9,900	31
8.25"	A2-5(I)	5500	9151-321__	.140"	.630"	2.05"	2.0"	5/16" UNC	6,200	15,000	53
8.25"	A2-6(D)	5500	9151-421__	.140Z	.630"	2.05"	2.0"	5/16" UNC	6,200	15,000	53
8.25"	A2-8(I)	5500	9151-521__	.140"	.630"	2.05"	2.0"	5/16" UNC	6,200	15,000	53
10.0"	A2-6(I)	5000	9151-426__	.160"	.730"	2.56"	2.5"	3/8" UNC	7,200	19,800	82
10.0"	A2-8(D)	5000	9151-526__	.160"	.730"	2.56"	2.5"	3/8" UNC	7,200	19,800	82
12.0"	A2-8(I)	4200	9151-531__	.160"	.730"	3.54"	3.0"	3/8" UNC	9,900	27,000	150
12.0"	A2-11(D)	4200	9151-631__	.160"	.730"	3.54"	3.0"	3/8" UNC	9,900	27,000	150
15.0"	A2-8(I)	3000	9151-538__	.200"	.790"	4.92"	4.5"	3/8" UNC	13,500	31,500	280
15.0"	A2-11(D)	3000	9151-638__	.200"	.790"	4.92"	4.5"	3/8" UNC	13,500	31,500	280
18.0"	A2-8(I)	2500	9151-546__	.236"	.984"	5.59"	5.5"	1/2" UNC	15,500	38,250	375
18.0"	A2-11(I)	2500	9151-646__	.236"	.984"	5.59"	5.5"	1/2" UNC	15,500	38,250	375
20.0"	A2-11(I)	2500	9151-650__	.236"	.984"	5.59"	5.5"	1/2" UNC	15,500	38,250	550
24.0"	A2-11(I)	1800	9151-660__	.315"	.984"	6.299"	6.25"	1/2" UNC	20,700	38,250	760
24.0"	A2-15(D)	1800	9151-760__	.315"	.984"	6.299"	6.25"	1/2" UNC	20,700	38,250	76

King Bore Chucks
7.0"	A2-5(D)	7000	9161-318__	.140"	.630"	2.20"	2.0"	5/16" UNC	4,500	13,000	37
8.25"	A2-6(D)	5500	9161-421__	.140"	.630"	2.59"	2.5"	5/16" UNC	5,400	15,000	53
10.43"	A2-6(I)	5000	9161-426__	.160"	.730"	3.03"	3.0"	3/8" UNC	7,200	19,800	82
10.43"	A2-8(D)	5000	9161-526__	.160"	.730"	3.03"	3.0"	3/8" UNC	7,200	19,800	82
12.40"	A2-8(I)	4200	9161-531__	.160"	.730"	4.05"	4.0"	3/8" UNC	9,900	27,000	183
12.40"	A2-8(D)	4200	9161-531__	.160"	.730"	4.05"	4.0"	3/8" UNC	9,900	27,000	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.

Dimensional and Performance Data (in inch)
Dimensional Data

						E
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

Dimensional and Performance Data (in inch)
					L
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"