Type
Booms, lift arms, levers and carriages welded to drawing
The moving member of a machine: a tapered box section boom with a forked pivot end, a telescopic boom section with a drilled collar, a pair of lift arms cranked to their pivot bores, a scissor arm frame, a swing arm of two side plates, a lever pair on a cross tube, a slide carriage with machined pads. The pivot bore and the pad are what the part is measured by.
The gallery holds these from a lever pair of a metre and a half to a scissor arm frame of six metres.
What the drawing must show
A part like this is priced from the drawing. The quotation is fastest when it carries:
- The bore diameters, their tolerances and the distance between bore centres
- Which bores and pads are machined after welding, and in which setting
- Plate thicknesses and section sizes with the material grade
- Weld symbols on the joints that carry load, and the inspection level
- The finish, and the bores that stay bare for a bush or a pin
8 models of this type
Real structures that came through this company as built jobs, quoted enquiries or designs from our own office, shown as anonymous models with their measured size. Open one for its description.
- Overall size, L x W x H
- 2 583 x 1 315 x 1 680 mm
A lift arm weldment made from two long parallel box-section arms, cranked down at one end into plate cheeks with pivot bores, tied together by a cross tube and gusset plates, with a hoop bracket and stub lug on top. The cranked, bored plate ends and the welded cross tube stand out. It measures about 2.6 m long, 1.3 m wide and 1.7 m high. Such a part is set on a fixture, tacked and welded out, then machined after welding on a horizontal boring mill.
- Overall size, L x W x H
- 3 137 x 650 x 755 mm
A tapered box section boom built from welded plate, with a forked pivot end carrying bored lugs on both sides and a bored eye at the tip. A lug plate sits near the pivot, with stepped plates and stops along the upper flange marking cylinder and hose positions. The forked ends and bored bosses stand out most. It measures about 3.1 m long, 0.7 m wide and 0.8 m high. A piece like this is tacked up on a fixture and welded through.
- Overall size, L x W x H
- 3 755 x 588 x 560 mm
A telescopic boom section built from a long welded box section, with top wear plates, internal stiffening ribs, a drilled end collar, a bored pivot head and mounting lugs at the other end. The open box end with its pattern of bolt holes and the machined pivot bores stand out. It measures about 3.8 m long and 0.6 by 0.6 m in section. Parts like this are tack welded on a fixture and welded out, then machined after welding on a horizontal boring mill.
- Overall size, L x W x H
- 5 989 x 972 x 309 mm
A scissor arm frame of this kind is built from two long box section rails joined by cross members, with diagonal bracing and pivot lugs forming an X pattern near both ends. Mid length there are bored pivot seats and a raised bracket pad set between the rails. It measures about 6.0 m long, 1.0 m wide and 0.3 m high. A piece like this is welded out on a fixture, with every bore and pad cut after welding.
- Overall size, L x W x H
- 2 730 x 728 x 1 022 mm
A swing arm weldment like this is built from two arched side plates joined by cross plates and a connecting tube, with a top plate at the peak and pivot lugs with bored eyes at both feet. The arched profile and paired bores at each end stand out. It measures about 2.7 m long, 0.7 m wide and 1.0 m high. Such a part is cut on the 2 000 x 4 000 mm laser bed, plate up to 20 mm and tacked up on a fixture and welded through.
- Overall size, L x W x H
- 2 890 x 1 990 x 693 mm
A slide carriage weldment built from a drilled base plate carrying two long parallel box beams, linked by angled ribs, gussets and short upright stiffeners, with web cutouts between them. The plate's bored round seat, square and oval cutouts, bolt pattern lugs and the machined pads along both beam tops stand out. It measures about 2.9 m long, 2.0 m wide and 0.7 m high. In this hall a part like this is tacked up on a fixture and welded through, with every bore and pad cut after welding.
- Overall size, L x W x H
- 1 089 x 930 x 1 243 mm
A heavy bracket weldment built from two tall, curved cheek plates with rounded tops and lightening holes, joined by a bored cross tube, a drilled deck plate and gusseted ribs down to a flat base with ring lugs and bolt holes. The bored pivot seat at the top and the flared base lugs stand out. It measures about 1.1 by 0.9 m and stands 1.2 m high. Such a part is laser cut up to 20 mm and welded out on a fixture.
- Overall size, L x W x H
- 1 361 x 454 x 699 mm
A lever pair like this is formed from two tapered plate arms joined by a long cross tube, with bored pivot holes at top and bottom and a small welded hoop lug on one lever. The faceted, planed plate faces and the machined bores where the tube meets each lever stand out. It measures about 1.4 m long, 0.5 m wide and 0.7 m high. Parts like this are tack welded on a fixture and welded out, with every bore and pad cut after welding.
Each model is rendered from its own geometry in raw steel, without paint, and is shown as a still. Customer names, machine designations and drawing numbers are not published; part lists and files are not offered. The interactive model above this section is a parametric example, not one of these.
How a part like this goes through the hall
Side plates are laser cut up to 20 mm, folded where the section allows, and the arm is welded on a fixture that holds the bore centres. Bores and pads are machined after welding on a boring mill, so the centres are cut from the welded piece. The arm is blasted and painted, and the bores are measured before it ships.
Where this fits
Capabilities it runs through
Industries that order it
Notes from the blog
Other types in this group
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