Serial hoists

Using chain blocks? This page tells you how to handle, maintain and inspect them.

Chain blocks and lever blocks are also known as serial hoists. They make operation and maintenance work easier. Using manual power, pneumatic and hydraulic power for operation, the lifting mechanism is designed to do most of the work for you.

Serial hoists are ideal for tight spaces and light duty applications. They have a typical lifting capacity of up to 30 tonnes.

Chain blocks

Serial hoists comply with AS1418.2 Serial hoists and winches.

Serial hoists are used for short term lifts and shifts. Serial hoists are not intended to be used for permanent installation or suspension of loads.

Typical applications for lifting include:

• monorail cranes
• portable jibs
• fixed hoists.

Fleeting

Serial hoists are often used by riggers for transferring or "fleeting" loads horizontally from anchorages in low headroom environments.
 

Example of fleeting

The transfer of loads horizontally is achieved by connecting at least two serial hoists of suitable capacity. Each hoist has to have capacity to hold the entire load on its own.

The first hoist suspends the load while the additional hoists are connected. After connecting the additional hoist, the load is moved by changing the length of the load chain on each hoist. Shorten the load chain on the additional hoist then extend the load chain on the first hoist. Repeat this process until the load is in the correct position.

Make sure serial hoists orientate freely without obstruction in the direction of the load. They should be aligned throughout their full range of motion.
 

Example of serial hoist misuse
 

Example of serial hoist misuse

With good communication and coordination of the rigging crew, fleeting can be a very smooth process.

Here is a simple example of fleeting from one hoist to another hoist:

Fleeting diagram

The maximum angle of any serial hoist is 45 degrees from vertical. Always check manufacturers' recommendations, as it may be less than 45 degrees.

To operate within the working load limit (WLL) of the hoist, the operator needs to apply a maximum of 30 kilograms of force to:

• the handle of the lever block, or
• the pull chain on a chain block.

Any effort greater than 30kg should be considered as overloading the block.

Lever blocks

Lever blocks are compact and lightweight. They are ideal for horizontal, angled and low vertical loads. Only one hand is required to operate lever blocks. The lever handle is next to the hoist suspension point. You must be within arms reach to operate the lever block.

Chain blocks

Chain blocks are mainly used for vertical lifting. Manual chain blocks can operate the pulling chain from the ground, even when the hoist is positioned up high. Chain blocks also allow very fine adjustment for precision raising, lowering or positioning.

Handling chain blocks

Do not drop a chain block. The jolt may distort the casing causing the gearing to malfunction and the chain block to fail. The drive pinion could also part from the main driving spur wheel.

Make sure that the hook has not flipped through itself in a two part or multiple chain fall. This would cause the load chain to twist.

Multi-fall hook blocks can roll over and jam the chain guides.
 

Example of six fall hook block

Example of three fall hook block

Maintenance of chain blocks

Chain blocks need to be maintained and kept clean. Some people keep the load chain lightly oiled to create less friction as the chain passes over the drive sprocket (also known as the gypsy).

Chain and drive sprocket

If the chain is oiled and it becomes covered in sand or grit, the grit becomes a grinding paste. This will wear the chain very quickly.

The drive sprocket in one manufacturer's chain block may not be identical to another. When ordering replacement chain, it is important that the chain and the drive sprocket are compatible.

How to inspect chain blocks

Chain and lever blocks should be inspected regularly.

When chain or lever blocks need repair, they will need to be retested to AS1418.2 by approved suppliers.

These hoists should never be saturated in lubricant or oils. This can cause brake slippage. Never leave a chain block soaking in oil or diesel.

Inspect the chain blocks

When inspecting chain blocks you should check:

• markings (manufacturer's ID, working load limit (WLL), serial number, size and grade of chain)
• the brake lining material for signs of wear. The brake should be assessed according to manufacturer's instructions.
• the pawl for sharpness, alignment and functionality
• the ratchet teeth for sharpness and wear
• the bearing bushes for wear and have them renewed if necessary.

Never disassemble a serial hoist unless trained and competent to do so. All repaired serials should be proof tested by appropriate testing authority to AS1418.2

Pre-use inspection

Here's what to check before using serial hoists:

• safety latches and swivel hooks are mandatory and must be functional
• check that ID plate is legible and includes Australian Standards, WLL, manufacturer and serial number
• make sure handle is not bent and is in working order
• make sure chain is not bent, gouged, cracked or stretched
• make sure hooks are not bent, gouged, stretched or cracked.

Chain and lever block pre-use inspection

Inspect the load chain

Check the load chain for grade markings, wear and stretch. Check the load drive sprocket for excessive wear. For example, polished metal or cracks.

If the load chain does not fit accurately, replace it before using the block.

Inspect the load chain guide

The purpose of the guide is to guide the load chain, free of turns, on to the drive sprocket.

Inspect the load chain guide for free movement.

If a roller guide is fitted, hang the block up. While lowering the empty hook, gently twist the ascending chain as it approaches the guide roller. If it jams, a new guide must be fitted.

Inspect the hooks

Here's how to inspect hooks:

• inspect the hook for wear (10%) and any damage or stretching
• make sure the hook swivels freely
• make sure the safety latch is fitted and operational. They are mandatory on serial hoists
• check the hooks for opening out due to overloading or misuse
• inspect the hook clevis and ball bearing swivels
• inspect the anchorages of chain to clevis pins.
   

Example of a stretched hook