RHA Excavator-Mounted Drill Drives
(Dangle Drills)

The MÜLLER RHA series hydraulic drill drives, commonly referred to as dangle drills, are powerful excavator-mounted drilling attachments designed for foundation construction, ground improvement, and pre-drilling applications. Suspended directly from the excavator stick or leader system, these units provide high torque and controlled rotation in a compact and durable design.

The RHA series is particularly well suited for high-speed pre-drilling operations, allowing contractors to efficiently penetrate dense soils, fill material, or overburden ahead of pile installation. This makes the units ideal for preparing holes for aggregate piers, sheet pile walls, pipe piles, soldier piles, and other deep foundation elements where fast and reliable drilling productivity is essential.

Powered directly by the excavator’s hydraulic system, the RHA drill drives deliver smooth torque and consistent drilling performance across a wide range of soil conditions. Their robust construction and modular mounting design allow for quick integration with various excavator sizes and drilling tools.

Key Features

  • High-torque hydraulic drill drive for foundation drilling applications
  • Excellent for high-speed pre-drilling of aggregate piers, sheet pile walls, and pile foundations
  • Compact “dangle” mounting design for flexible excavator operation
  • Compatible with a wide range of excavator sizes with quick installation
  • Heavy-duty construction designed for demanding jobsite environments
  • Hex output shafts for easy connection to augers and drilling tools
  • Adjustable speed and torque depending on hydraulic flow

Specification

RHA 12

RHA 16

RHA 24

RHA 34

RHA 46

Max Torque

8,850

11,800

17,700

25,080

33,930

Speed Range

30–125

30–115

30–110

30–100

30–70

Operating Pressure

1,160–5,076

1,160–5,076

1,160–5,076

1,160–5,076

1,160–5,076

Hydraulic Flow

13–204

20–273

23–359

32–469

47–469

Required Oil Flow

17–69

25–92

34–121

48–159

69–159

Min Drill Diam

8

8

16

16

16

Max Drill Diam

28

35

47

55

63

Max Depth (ft)

66

82

46

52

66

Max Depth (in)

13

13

6.5

6.5

6.5

Weight (US tons)

0.33

0.40

0.49

0.66

0.84

Height (in)

38.7

45.2

45.2

48.6

48.8

Drive Diam (in)

16.7

15.7

15.4

19.1

21.9

Hex Output (in)

2.75 / 2.75

2.75 / 3.15

3.15 / 3.15

3.94 / 3.94

4.72 / 4.72

Rec. Excavator (tons)

11–22

16.5–27.5

22–33

31–44

38.5–55

Rec. Power Unit

107–168

161–201

168–295

215–587

193–587