Spider lifts: when to use one and how to choose between the JLG X17JP and X20JP

In short: a spider lift is a compact articulating boom on tracks that works on four outriggers. At around 0.8 m wide and 2.2 to 3.1 tonnes, it goes through doors, gates and corridors where a standard boom lift won't fit. In JLG's range, the X17JP reaches 16.96 m of working height and the X20JP 20.15 m. To choose between them, start with the height and outreach you need, then check the access width, the load the floor can take and the power you can use on site.

What is a spider lift

It is called a spider because of the four outriggers that fold out around the chassis before the boom goes up. It moves on rubber tracks, with the operator walking alongside it using a remote control, and only works at height once it has been stabilised and levelled. JLG calls it a "compact crawler". It is also known as a tracked boom or tracked spider lift.

Unlike a self-propelled boom lift, it does not drive with the platform raised: it gets to the spot, deploys the outriggers, levels itself and only then starts work. In return, it is much narrower and lighter, and the platform can be removed to get through tight spaces.

When to use a spider lift

• Narrow access. Doors, gates, corridors and inner courtyards. With the platform removed, the X20JP drives through a standard 0.80 m door, and the X17JP is 0.80 m wide.
• Delicate floors and lawns. The tracks and outrigger pads on the X17JP and X20JP are non-marking, and track pressure stays below 0.7 daN/cm².
• Interiors. Atriums, shopping centres, churches, theatres, museums and historic buildings, where you need height but space and floor strength are limited. With the electric motor or lithium battery, it works without fumes.
• Sloping or uneven ground. The outriggers level the machine on slopes of up to 12°, and the tracks climb gradients of around 28%.
• Tree work and gardens. Pruning and tree care in estates, gardens and parks where a truck-mounted platform can't get in.
• Façades, heritage and glazing. Cleaning, painting, lighting and repairs on façades, cloisters and glass roofs, with the boom reaching over obstacles.

Outriggers, levelling and ground pressure

How they work

The four outriggers lift the machine off its tracks and form a base of around 2.9 × 2.9 m, much wider than the machine itself. On the X17JP levelling is automatic. The X17JP cuts out movements if the machine is off level and has a platform load sensing system. These systems help, but they don't replace checking the ground.

Ground pressure

The pressure under one outrigger reaches 2.45 daN/cm² on the X17JP and 3.04 daN/cm² on the X20JP, or roughly 245 to 304 kPa at a single point. That is much more than under the tracks, because the whole weight, plus the load and the effect of the boom, is concentrated on four pads. According to IPAF, the load capacity of the surface must exceed the machine's maximum ground bearing pressure, and the highest load may be on the side opposite the platform.

• Confirm the capacity of floors, slabs, basements and car parks with an engineer or the building owner.
• Use load-spreading pads under the outrigger feet whenever the ground is soft, fragile or uncertain.
• Look for covers, drains and trenches near the pads.

Comparison: X17JP and X20JP

The X17JP and X20JP are the two spider lifts JLG offers in Europe. They share the same concept (tracks, four outriggers, removable platform, 230 V electric motor), but differ in height, outreach and weight.

Which one for which job

X17JP: the most versatile for interiors and gardens

With 16.96 m of working height, 2,190 kg and 0.80 m width without the platform, it is the natural choice for churches, atriums, residential blocks, gardens and tree work. It is the lighter of the two, which makes transport and work on load-limited floors easier. The optional narrow platform (0.61 × 0.78 m, one person) helps in very tight spaces.

X20JP: more height and outreach

With 20.15 m of working height, 9.05 m of outreach and 8.20 m of up-and-over height, it suits tall façades, church naves, sports halls and large trees. It is heavier (2,900 to 3,100 kg) and puts more pressure on the outriggers, so check the ground even more carefully. Unlike the X17JP, it is available in a bi-energy version (lithium and diesel).

Rule of thumb: if you need up to about 17 m of working height and access or floor strength is limited, the X17JP will do. If you need more height, more side reach or to work over taller obstacles, go for the X20JP.

Transport

Both fit on a plant trailer or a flatbed truck, standing about 2 m high when stowed. Weight is what matters most when choosing the trailer: from 2,190 kg for the X17JP to 3,100 kg for the bi-energy X20JP. Choose a trailer or truck suited to the real weight of the version you have. Both have forklift pockets and lifting eyes for crane lifting, which helps when the machine has to go onto a roof terrace or into an enclosed courtyard.

Power: indoors or outdoors

• Electric motor (230 V on the X17JP and X20JP). For work inside buildings, plugged into the mains, with no fumes and little noise.
• Lithium battery (option). Cable-free, zero-emission work, with around 4 hours' charging time. Ideal indoors with no socket nearby. Find out more in our guide to diesel or electric platforms.
• Petrol or diesel. For outdoor work, trees and sites without power. Do not run combustion engines in enclosed spaces.
• Bi-energy (X20JP). Lithium and diesel on the same machine, for jobs that move between indoors and outdoors.

Safety

• Training. The operator must be properly trained (Portuguese Decree-Law 50/2005). Spider lifts fall under IPAF category 1b (static boom). See our guide to the IPAF (PAL) card.
• Ground assessment. Before setting up, check the surface, slopes, basements and buried services. Walk the route first.
• Travelling. On uneven ground, IPAF recommends tracking the machine with the outriggers partly deployed and the tracks in the extended position.
• Wind and loads. Respect the platform capacity and the wind limit shown on the machine's plate and in its manual.
• Inspections. Platforms must be inspected periodically by law. See our guide to mandatory inspections.

Buy or rent?

If you only need a spider lift a few days a year, renting usually pays. See how much it costs to rent a platform and our directory of rental companies. If you work regularly in interiors, gardens or heritage sites, owning the machine gives you immediate availability. We explain the options for financing the purchase.

How Trapézio can help

We are JLG's official dealer in Portugal. We help you choose the right model and version based on height, access, ground and available power.

• New machine sales: X17JP and X20JP.
• Used machines: see the used JLG platforms available.
• Service and parts: JLG after-sales service, genuine parts and manuals.

Tell us about the job and the site and request a quotation, or get in touch.