The DSM / Mayhew 1000 “Little Bobcat”

 Rig Specifications and Features

This drill is recommended for operation with a maximum drill string static load (including yoke, swivel, kelly, drill pipe, collars, etc.) of 20,000 lb (9,072 kg) on three lines. When operating with static load near maximum, avoid inducing dynamic loads that may cause the total load to exceed maximum. Operation exceeding this limit may result in equipment overload and possible collapse or falling components that may be hazardous to personnel.

MAXIMUM CAPACITIES OF PRIMARY LOAD BEARING COMPONENTS (Based on equipment that is new or in top condition under proper operating procedures)

Component                                                                                        Maximum Capacity

Mast                                                                                           35,000 lb                15,876 kg

Little Giant Swivel (2 in)                                                              32,800 lb               14,878 kg

DSM TB-10 Traveling Block                                                         20,000 lb               9,072 kg

DSM 24M Drawworks (Single line pull, bare drum)                     10,000 lb               4,536 kg

Sandreel (Optional) (Single line pull, bare drum)                        10,000 lb                4,536 kg

Consult the manufacturer for capacities of components other than these standard components. If you substitute an alternate component to increase capacity, be sure you do not exceed the load- bearing components.


1,000 ft (396 m) using 2 7/8 in (73 mm) drill pipe
1,500 ft (610 m) using 2 3/8 in (60 mm) drill pipe
(Recommended drilling depth based on favorable drilling conditions)


Model: 603 Mayhew, 5 1/4 in square drive, non-retracting
Type: Enclosed ring gear and pinion
Standard Opening – 7 ½ in (191 mm)
Frame Opening with Table Retracted – 16 in (406 mm)
Transmission: 9 speeds forward, 2 reverse
Clutch: Mechanical with two 8 in (203 mm) friction plates
Lubrication: Enclosed oil bath
Optional: DSM/Mayhew RT 7.5, Hydraulic retracting

DRAWWORKS (Drilling and hoisting lines)

Model: DSM/Mayhew 24M
Single Line Pull (bare drum): 10,000 lb (4,536 kg)
Typical line speeds: 310 ft/min. (94 m/min.)
Spooling capacity (each drum): 270 ft (82 m) of 5/8 in (16 mm) line
Drilling line: 270 ft (82 m) of 5/8 in (16 mm) line
Hoisting line: 270 ft (82 m) of 5/8 in (16 mm) line
Barrel size: 8 in (203 mm) dia. x 9 in (229 mm) long
Drive: Torque tube to drawworks ring gear and pinion
Clutches: Mechanical, with three 11 in (279 mm) friction plates
Brakes: Single band on drum – 6 in (152 mm) wide x 16 in (406 mm) dia.
Net braking area (each drum): 288 in sq. (1,858 cm sq.)


Power: Hydraulic through planetary gear box with 10,000 Series Eaton-Charlyn Motor
(Optional: Hydraulic drive)
Feed: 1 1/2 in (38 mm) pitch single roller chains
Engagement: Mechanically actuated jaw clutch mechanism
Kelly guides: Channel type

SANDREEL (Optional)

Single Line Pull (bare drum): 10,000 lb (4,536 kg)
Typical line speeds: 183 ft/min. (56 m/min.)
Spooling capacity: 1,500 ft (457 m) of 3/8 in (10 mm) line
Barrel size: 6 1/2 in (165 mm) dia. x 20 7/8 in (530 mm) long
Drive: Chain from drawworks shaft
Clutches: Air, with three 11 in (279 mm) friction plates
Brake: Single band on drum – 6 in (152 mm) wide x 16 in (406 mm) dia.
Net braking area: 288 in sq (1,858 cm sq.)


Maximum capacity: 35,000 lb (15,876 kg)
Overall length: 32 ft (9.75 m) Optional: 36 ft (10.97 m) to 38 ft (11.58 m)
Construction: Tubular, box type, electrically welded
Drawworks sheaves: Six 10 1/4 in (260 mm) dia. with bronze bushings
Pulldown sheaves: Two 10 1/4 in (260 mm) dia. with bronze bushings


Model: DSM 2 in (50.8 mm) Little Giant
Watercourse: 2 in (50.8 mm)
Bearing capacity: 32,800 lb (14,878 kg) at 100 rpm
Service: Air or mud
Main bearing: Timken tapered roller


Model: DSM/Mayhew TB-10 (Optional ST-10, weighted)
Capacity: 20,000 lb (9,072 kg)
Sheaves: One 10 in (292 mm) dia.


3 5/16 in (84 mm) dia. x 23 ft (7 m) long with three 3/4 in (19 mm) drive pins

                                                           PTO                                   TRANSFER

Model:                                                 DSM 2001D                       DSM 602R

Type:                                                   Split shaft, full torque          Chain Case

Chain:                                                  Quad                                   Quad

Bearings:                                             Ball                                       Ball

Sprockets:                                           Heat treated                          Heat treated

Lubrication:                                          Oil bath                                 Oil bath


435 cfm (12,318 lpm) to 500 cfm (14,158 lpm) Vanair
Drive: Hydrostatic


Pump 1: Positive displacement, gear type, 9 gpm (34 lpm) to 16 gpm (61lpm)
Pump 2: Pulldown system only – Variable volume piston pump, 17 gpm (64 lpm) at 2000 psi (140.6 kgf/cm sq.)
Pump drive: Direct coupled into transfer unit
Mast raising cylinders: Twin, double acting, single stage with flow restrictors
Leveling Jacks: Two jacks mounted on rear of drill, 6 in. (152 mm) stabilizer with 5 in (127 mm) dia. piston. Optional: Front 36 in (914 mm) mounted behind the cab
Type fluid: ATF type F or Rando
Reservoir capacity: 50 gal (189 l) max.
Filters: Full flow type with built-in 10 micron bypass


Grouped at driller’s position for one man operation. Mechanically operated for drawworks and air compressor. Air actuated clutches on mud pump. Mechanical, lever actuated pulldown jaw clutch engagement. Mechanical actuated clutch on rotary. Hand operated air throttle. Kill switch and tachometer mounted in control panel. Expanded metal driller’s and helper’s platform.

MUD PUMPS (Gardner-Denver power pumps)

                                                           Standard                                   Optional

Model:                                                 FG-FXG                                     FD-FXX

Displacement (max. rpm)                  150 gpm (568 l/min)                   222 gpm (840 l/min)

Max. operating pressure                   310 psi (21.8 kgf/cm sq)             338 psi (23.8 kgf/cm sq)

Linear diameter                                 5 in (127 mm)                             5 1/2 in. (140 mm)

Stroke                                                6 in (152 mm)                             8 in. (203 mm)

Suction hose                                      4 in (102 mm)                            4 in. (102 mm)

Typical operating speed                    75 strokes/min                           70 strokes/min.

Drive                                                  Chain or belt                               Belt

Clutch Standard: Air actuated mechanical with three 8 in. (203 mm) friction plates.
Clutch Optional: Three 11 in. (279 mm) on FD-FXX

Manifolding Relief valve, pressure gage and surge chamber. Hinge hose, stand pipe and swivel hose: 2 in. (50.8 mm)


Variable volume, hydraulically driven, FMC Bean, 9 gpm (34 l/min), 600 psi (42 kgf/cm sq) with relief valve.