Choosing the right Crane
When you need a crane, remember to always tell us as much as you possibly can about your intended use of the crane.
- What is the actual weight of the load you are lifting?
- How often you will be using the crane?
- Describe the load.
- What is the required height of lift?
- What is the length of long travel (down shop) & cross travel (span)?
- Do you need single or two speeds?
- What controls – pendant or radio remote?
- What will be the power supply?
- What is the general environment? Are there any special requirements?
Make of crane
These days most European cranes are inherently safe and operator friendly. They do not break down unless you abuse them. However, when you buy a crane make sure that it is a well proven make with excellent local spares and service backup as a guarantee may be of little use to you if the spare parts are not readily available.
Working load
The Safe Working Load, or Working Load Limit, is the maximum load which can be safely lifted by the crane. Tell us the actual load you are lifting and do not round it up yourself. Also tell us how often you will lift the load. We will then be able to propose the most appropriate crane type to suit your needs.
Crane duty
Crane duty ranges from light to very heavy and we are best able to advise on this after carefully considering all the other information you let us have.
Type of load
Tell us as much as possible about the load, its size, shape and what it consists of.
Height of lift
This is measured from the crane hook’s lowest position (usually the floor) up to the highest position. If possible, tell us the exact height of lift required.
Headroom
This is the distance between the highest point of the crane structure and the load hook in its highest position. Some cranes are designed to be low/close headroom so that you can maximise the height of lift within the constraints of your building.
Speed of lift
Some crane applications only need single speed hoisting and travel but two speed (fast and slow) is essential where precise load positioning is required or where the load is such that it is safer to make the initial lift at a slow speed. Some manufacturers now offer variable speed.
Travel functions
These days most cranes are electrically powered but a cheaper option is to have manual operation. This is not recommended over 1.5 tonnes and the trolleys tend to travel in ‘jerks” of one or two feet at a time so accurate load positioning can be difficult. Electric power travel is best because the crane travels effortlessly with the simple push of a button and you can have either single speed or two speed operation.
Supporting gantry and crane rails
A crane can be supported by, and run on, a totally free-standing gantry or on crane rails fixed to an existing building structure. Sometimes it can be a combination of both. Another type is the Goliath crane where the crane runs along rails at floor level or Semi-Goliath running on high level crane rails at one side and on floor rails at the other side.
Control
Most cranes are supplied with a low voltage pendant control which is a push button box suspended from the hoist unit on a cable or suspended from a separate cable festoon track so that the operator can stand well away from the load. The pendant can be any length to suit the job.
Another option is remote control by either radio or infra-red. Radio control is the more versatile but bear in mind that the operator does not need to be in sight of the crane to operate it so care should be taken to ensure that the handset is only used by responsible people and with great care.
Infra-red requires line of sight between the handset and the sensor on the crane and this can be a safety feature but the sensors on the crane must be cleaned regularly otherwise they get dusty and will not function. All controls can be supplied with a key operated isolator switch for security and safety.
We recommend that all remote-control cranes are supplied with a spare plug-in pendant as a backup just in case the remote control fails, often the handsets get lost, damaged or need charging.
Safety features
Most cranes these days are fitted with overload protection preventing the hoist unit from lifting more than its safe working load. Slipping clutches are sometimes used for this purpose and they also prevent over hoisting and over lowering. Limit switches also prevent over hoisting and over lowering.
Environment
Indoor, warm, and dry or outdoor, cold, and wet?
Is the atmosphere hazardous requiring explosion or fire-resistant measures? Is there a lot of dust or other contaminants?
Enclosure protection
Most cranes are protected to IP55 (dust and water resistant) as standard which covers most normal environments, but you may wish to consider additional protection for cranes which are permanently outdoors. An outdoor crane should also be fitted with a hoist weather protection canopy.
Chain Hoists / Wire Rope Hoists
Chain hoists are cheaper and usually preferred up to 5 tonnes, they require less maintenance, tolerate more abuse, chain can last 30 times longer than wire rope, more allowance for side pulling, and they have a true vertical lift. Wire rope hoists tend to be quieter, smoother, have faster lifting speeds and are generally preferred over 5 tonnes especially for long lifting heights and for heavy duty use. There are other pros and cons and we will advise on these according to your specific requirements.
Electric power supplies
In the UK it is normal to use 400volt 3 phase 50Hz power supplies.
Pneumatic power supplies
Most pneumatic cranes operate on an air pressure of approx. 90psi or 6 bar, but it is important to realise that they need a reasonable volume of air supply to operate properly. Typically, hoists up to 2 tonnes capacity consume air at approx. 22 litres/second.