Halco Rock Tools, UK Manufacturer of DTH Hammers and Bits. Halco pioneered the development and distribution of DTH hammers in the 1950s.
The GP400 high performance hammer drills under a head of water typically suited to Waterwell and Geothermal applications due to its non-ported piston design.
 
It features a choke facility which helps to adjust air flow through the hammer.
A choke facility is housed within the N.R.V. to allow adjustment of air flow to improve flushing. 
3/16" Plug
1/8" Plug
Blank
Plug
Revised chamber volumes and cycle timing to optimize performance.
Simplified piston geometry for improved balance and location within cylinder.
Air Consumption
A captive bit retaining ring makes changing the drill bit easier.
Size
110-140mm
(4 5/16-5 1/2")
Shank
DHD340A
TD 40
Air Pressure
100-435PSI
(7-30 bar)
DHD340A
Tech Specs
TD 40
Tech Specs
Overview
GP400
Hammer Type
Part Number
Shank
Top Thread
Hammer Flat Size
Weight
Outside Diameter
Make Up Length
Recommended Maximum Thrust
600425
DHD 340A
2 3/8" API Reg Pin
66mm (2.560") 
40Kg
98mm (3.858")
954mm (37.559")
500Kg (1100 lbs)
600444
TD 40
2 3/8" API Reg Pin
66mm (2.560") 
40Kg
98mm (3.858")
954mm (37.559")
500Kg (1100 lbs)
Drill Bit Overview
DHD 340A
Oversize
 
 
 
 
 
 
Y
Y
Y
Y
Y
Y
Diameter
Face
Buttons
Part
Number
650949
650961
653091
650526
650625
650955
650967
650680
650611
650966
650013
653482
650614
653094
Weight
(Kg)
8.1
8.1
8.5
8.2
8.2
8.3
8.5
10
9.5
9.6
10.6
9.7
10.1
11.8
Design
Convex
Convex
Convex
Convex
Concave
Flat
Convex
Concave
Concave
Concave
Convex
Convex
Concave
Concave
Type
Dome
Semi Ballistic
Parabolic
Dome
Dome/S-Ballistic
Dome
Semi Ballistic
Dome/S-Ballistic
Dome
Semi Ballistic
Dome
Ballistic
Dome/S-Ballistic
Dome
mm
110
110
110
115
115
115
115
120
127
127
127
127
130
140
 
Inch
4 5/16
4 5/16
4 5/16
4 1/2
4 1/2
4 1/2
4 1/2
4 3/4
5
5
5
5
5 1/8
5 1/2
 
Qty & Dia
15 x 13mm
15 x 13mm
14 x 14mm
16 x 13mm
8 x 14 / 6 x 13mm
8 x 13mm / 8 x 13mm
8 x 14mm / 10 x 13mm
8 x 13mm / 8x 13mm
16 x 13mm
16 x 13mm
16 x 13mm
20 x 13mm
8 x 14mm / 8x 13mm
9 x 16mm / 9 x 14mm
 
Additional bit configurations are available on request.
TD40
Oversize
 
Diameter
Face
Buttons
Qty & Dia
 
8 x 16 / 6 x 13mm
8 x 16mm / 6 x 13mm
Part
Number
653624
653647
 
Weight
(Kg)
10
10
mm
116
116
 
Inch
4 1/2
4 1/2
Design
Flat
Flat
Type
Dome
Parabolic
Additional bit configurations are available on request.