Product Bulletin Release No.1 Oct 2002

LASHING GEAR

ALSO KNOWN AS “MUCKING UNITS”

 

 

1. Purpose

The objective of the Lashing Gear is to provide a means of clearing a blast of rock during shaft sinking operations as quickly and safely as possible.

2. Overview

Winder Controls (Pty.) Ltd. manufactures a range of Lashing Gears to suit a range of cactus grab sizes and finished shaft sizes.

The following table gives our standard range of Lashing Gears:

3. Features

The Lashing Gear is a self-contained unit using only compressed air as the motive power. The air is fed, via a main shut off valve, filter and lubricator, to the swivel joint, and then to the operator’s valves for control of the relevant motion air motor, all of which are mounted on the Lashing Gear.

The Lashing Gear is of composite construction having the hoist assembly and the slew drive unit mounted on the turntable, this in turn is carried on the base by means of a combined slew bearing and internal gear.

The base is mounted directly on the bottom deck of the stage.
The boom, from which the cactus is suspended, is mounted below the bottom deck and secured to the underside of the turntable.

An operators cabin is mounted below the boom and on the vertical centre line of the Lashing Gear providing good visibility and unrestricted directional rotation in the shaft.

The Lashing Gear is provided with four operational functions:
· Left hand lever for Hoisting and Lowering.
· Right hand lever for Cactus grab Opening and Closing.
· Left foot pedal for Turning Right and Left.
· Right foot pedal for Traversing In and Out.

The Operator also has access to a manual shut off valve that isolates all air supply to the cabin, thus putting the Lashing Gear into a safe mode.

Other controls on the Lashing Gear unit are:
· Emergency air shut off valve.
· Auxiliary hoist valve on the turntable for use when reeving in a new hoist rope.

4. Specification

BASE MOUNTING SUPPORT
The base mounting support is fabricated from standard plate steel and of heavy enough section to transmit the imposed loads from the main support bearing and turntable. The base is drilled around the perimeter to take the mounting bolts, these are spaced to provide greater strength at the base corners adjacent to the stage vertical supports.

After stress relieving the base mounting plate is accurately machined with a spigot and drilled in the centre to take the support ball bearing.

TURNTABLE

The turntable comprises the upper support ring for the ball race and the integral hoist winch and slew gearbox base plate. The turntable is designed to support the Lashing Gear boom section by means of two longitudinal pins made of forged steel.

The turntable base member is fabricated in heavy steel plate with rolled steel sections providing the winch and slew gearbox mounting members, stiffening sections are also fitted in the base section.

The turntable is amply welded with large radius fillets and stress relieved before machining.

The lower face of the turntable is machined to take the ball race mounting. The upper face being machined to facilitate the alignment of the winch and slew gearbox components.

BOOM

The boom is fabricated from steel plate through out. The side plates are cut from a single sheet thus eliminating butt welded seams or spliced joints giving greater strength. The boom is of rectangular or oblong section having the greater sides parallel to the bottom extension, thus providing the maximum moment of inertia to resist the couple imposed by the suspended load.

The mounting connection of the boom is reinforced with heavy steel plate to distribute the compressive stresses at the mounting pin holes which in turn are machine bored for alignment accuracy.

Square section steel wheel tracks are secured on welded supports along the boom arm section and are amply reinforced by a rolled steel section on the outer faces of the boom.

The end plate is provided with a large radius rope guide, and an anchor block is mounted on the boom rope surface to facilitate rope replacement.

The boom deflector sheave is carried in a slide block and accessible for easy removal from the rear of the boom. Provision is made on the bottom face of the boom to carry the operator’s cabin, which in turn is simply connected for quick removal whenever the Lashing Gear is installed or removed from the stage.

TRAVERSE CARRIAGE

The traverse carriage is made up of profiled steel side plates and welded into a composite chassis with pulley and wheel bearing bosses fully inset into the side plates. All bosses are accurately machined to take the bearings and the carriage is designed to facilitate replacement of components on site.

The deflector pulley and track wheel axles are of forged steel. Pulleys and track wheels are of cast or forged steel.

Provision is made for the transverse air cylinder connection pins on top of the carriage. The unit is stress relieved after welding and before machining.

HOIST WINCH

The hoist winch has a totally enclosed spur geared reduction case with integrally built outboard pedestal and provision for flange mounting the drive air motor. The air actuated brake acts on the second motion shaft, and a rope drum is carried between the pedestal and the gearbox.

The gearbox is of fabricated construction and split through the centre line. The bottom half of the box is built integral with the outboard drum pedestal. Bearing bosses are line bored to ensure correct alignment of the shafts. A flanged steel plate connection is provided for the mounting, through a splined shaft, of the air motor to facilitate its replacement.

The final motion gear set is a straight spur with a 20° pressure angle, the gear itself is a fabricated construction with a forged steel rim. The pinion is of forged steel.

The motion gears are of single helical design with a 20° pressure angle. The gear is a fabricated construction with a forged steel rim and the pinions of forged steel. Shafts are of forged steel and are accurately machined to receive their various components.

A rope drum of fabricated construction is press fitted and keyed to the final shaft. The drum is accurately machined through the bore after stress relieving and provided with a suitable rope anchor point.

A winch brake of the floating shoe calliper type is provided. The brake is applied by a spring and released by an air cylinder, making it a “fail to safety” mode. The brake drum is of steel fabricated construction, stress relieved before machining and is amply rated for the maximum design duty.

Wire rope protection guides are provided around the drum flanges.

SLEW DRIVE

The slew drive comprises a totally enclosed spur gear reducing case with shafts mounted vertically in order for the final pinion to mesh with the slew gear mounted to the turntable. The pinion is carried integrally with the slew gear case.

The drive motor is direct mounted vertically with a splined shaft extension coupled to the first motion shaft, the motor being flange mounted to the gear reducer.

The gears, of which there are two motions, are of straight spur 20° pressure angle on the final motion and a single helical 20° pressure angle on the first motion. The gears are of fabricated construction with a forged steel rim and the pinion of forged steel. Tooth faces are of ample width for the design duty.

The gear case is of dished construction having a flanged top plate cover. All bores are line bored to receive the bearings, and all fabricated items are stress relieved before machining.

Although the reduction ratio required for the slew drive could be achieved using a more compact and less costly worm and wheel gearbox, the reversal of direction during slewing operations would apply extremely high loads to the worm and wheel and has been known to be the cause of failures in previous designs.

Ample holding down bolt positions are provided to withstand the high torque loads applied.

AIR SWIVEL JOINT

The main air swivel joint is of special design comprising inner and outer components. The main supply air to the motors and grab valves being taken through the centre. Machining of the swivel unit is accurate and sealing is obtained through the use of labyrinth seals.

PIPING OF AIR SYSTEM

The use of air hoses, which are of course susceptible to damage, has been avoided and all air lines have been piped in steel. Being grouped together inside a steel channel further protects small diameter air lines.

OPERATOR’S CONTROL VALVES

These are of the treadle and lever operated type. An emergency control valve is also provided to actuate the main air supply valve. The cactus grab operating valve is a poppet valve unit which is remotely operated by a pilot valve to ease the operators control - alternatively a direct operating valve of the balanced spool type can be provided.

IN LINE LUBRICATION

A steel fabricated tank type lubrication unit is provided which is to be mounted in the supply air line on the second stage deck.

CACTUS GRAB CROSSHEAD

The crosshead is fabricated from steel plates with a cast steel or fabricated sheave mounted on an axle and running on two sealed ball bearings. The crosshead is fitted with two compression springs at each grab rope anchor point to absorb shock loads induced by the grab.

OPERATOR’S CABIN

The cabin is fabricated from steel plate, the lower portion is tapered for the deflection of blast fragments of rock. The cabin is bolted to the boom section for quick removal, and an operator’s seat is provided in addition to air manifolds and pipe work.

LUBRICATION

All gear with the exception of the slew ring gear are fully enclosed and oil lubricated. The ring gear is protected and grease lubricated. All other moving parts, with the exception of the carriage and grab crosshead, are lubricated from a centralised grease lubrication system, thereby reducing maintenance down time to a minimum.

MAIN SUPPORT BEARING (SLEW BEARING)

The main support bearing is a massive ball race of between 1000mm and 2200mm in diameter depending on the type of lashing gear selected. It carries both the axle thrust due to the mass of the lashing gear and its load, and the turning moment produced by the boom load. The bearing is designed to be capable of withstanding loads far in excess of the maximum design loads which would be imposed in service. The ring gear for the slew drive is cut in the inner race of the bearing.

TESTING

The Lashing Gear unit is fully shop erected and tested to the satisfaction of the client’s Engineer.

5. General

A comprehensive Operation and Maintenance Manual, giving lubrication guidance, instructions on how to reeve in a new hoist rope, detailed parts list for ordering spares, and assembly drawings, is provided.
Assistance with installation and commissioning of the Lashing Gear can be provided at a fee.