# LEGO 42121-1 — Heavy-Duty Excavator (2021)

Source: https://www.brickmissing.com/sets/42121-1-heavy-duty-excavator
Publisher: BrickMissing (https://www.brickmissing.com) — free LEGO parts checker. Not affiliated with the LEGO Group.

The LEGO Technic Heavy-Duty Excavator (42121-1) offers an intricate look at construction machinery. This 569-piece model features a shovel that moves up and down, a movable arm, and running belts for movement. The excavator body rotates 360 degrees, and its cabin includes a driver's seat and control panel. The set comes with LEGO brick ‘stones’ for digging and four cones. As a 2-in-1 build, the model reconstructs into a tracked tractor equipped with a backhoe, demonstrating Technic's mechanical design principles.

## Set facts

- Set number: 42121-1
- Name: Heavy-Duty Excavator
- Theme: Technic
- Released: 2021
- Pieces: 569
- Distinct part + colour lots: 116
- Build difficulty: intermediate
- Repairability: 0.9% of this set's lots are hard to replace (1 of 116 part+colour combinations appear in three or fewer sets in the entire LEGO catalog).

## Complete parts list (116 lots, 569 pieces)

Prices are the official LEGO Pick a Brick price per individual part, where LEGO publishes one.

| Qty | Part | Colour | Part no. | LEGO element ID | LEGO price each |
| ---: | --- | --- | --- | --- | --- |
| 6 | Technic Gear 8 Tooth [Reinforced] | Dark Bluish Gray | 10928 | 6012451 | €0,15 |
| 7 | Technic Axle Pin 3L with Friction Ridges Lengthwise and 1L Axle | Red | 11214 | 6209519 | €0,29 |
| 1 | Slope Curved 2 x 1 No Studs [1/2 Bow] | Red | 11477 | 6029946 | €0,06 |
| 2 | Technic Beam 1 x 5 Thin with Axle Holes on Ends | Black | 11478 | 6327028 | €0,25 |
| 1 | Technic Panel Fairing #22 5L Small Smooth, Side A | Yellow | 11947 | 6352686 | €0,38 |
| 4 | Slope Curved 2 x 2 x 2/3 | Yellow | 15068 | 6079007 | €0,13 |
| 86 | Technic Link Tread with Beveled Edge | Black | 15379 | 6047885 | €0,13 |
| 1 | Plate Special 1 x 2 with 1 Stud with Groove and Inside Stud Holder (Jumper) | Black | 15573 | 6092585 | €0,06 |
| 1 | Technic Gear 20 Tooth Double Bevel with Axle Hole Type 1 [+ Opening] | Tan | 18575 | 6346517 | €0,36 |
| 12 | Technic Axle Pin 3L with Friction Ridges Lengthwise and 2L Axle | Black | 18651 | 6089119 | €0,08 |
| 5 | Technic Pin Connector Round 1L [Beam] | Black | 18654 | 6121485 | €0,05 |
| 1 | Technic Pin Connector Round 1L [Beam] | Light Bluish Gray | 18654 | 6183784 | €0,05 |
| 2 | Plate Special 1 x 2 with Pin Hole Underneath | Black | 18677 | 6192309 | €0,07 |
| 1 | Technic Turntable Large Type 3 Top, 60 Tooth | Black | 18938 | 6109283 | — |
| 1 | Technic Turntable Large Type 3 Base | Light Bluish Gray | 18939 | 6109285 | €1,04 |
| 7 | Technic Pin Connector Hub with 1 Axle | Dark Bluish Gray | 22961 | 6135014 | €0,13 |
| 3 | Technic Panel Curved and Bent 6 x 3 | Yellow | 24116 | 6133245 | — |
| 1 | Technic Panel Curved and Bent 6 x 3 | Trans-Clear | 24116 | 6133686 | — |
| 1 | Technic Digger Bucket 4 x 7 | Dark Bluish Gray | 24120 | 6471569 | €1,59 |
| 4 | Tile Special 1 x 2 Grille with Bottom Groove | Black | 2412b | 241226 | €0,06 |
| 10 | Technic Axle 3 with Stop | Reddish Brown | 24316 | 6135494 | €0,07 |
| 1 | Technic Pin Connector Hub with 2 Axles | Dark Bluish Gray | 27940 | 6167281 | €0,17 |
| 1 | Plate 2 x 2 | Black | 3022 | 302226 | €0,10 |
| 1 | Plate 1 x 2 | Yellow | 3023 | 302324 | €0,08 |
| 1 | Plate 4 x 6 | Yellow | 3032 | 303224 | €0,41 |
| 2 | Tile 1 x 2 with Groove | Light Bluish Gray | 3069b | 4211414 | €0,07 |
| 2 | Tile 1 x 1 with Groove | Red | 3070b | 307021 | €0,05 |
| 1 | Technic Brick 1 x 2 [2 Pin Holes] | Black | 32000 | 3200026 | €0,10 |
| 4 | Technic Pin 3/4 | Tan | 32002 | 6013938 | €0,08 |
| 2 | Technic Beam 1 x 11.5 Double Bent Thick | Yellow | 32009 | 6271150 | €0,39 |
| 1 | Technic Axle and Pin Connector Angled #1 | Black | 32013 | 6284699 | €0,08 |
| 3 | Technic Axle and Pin Connector Angled #6 - 90° | Black | 32014 | 6268905 | €0,22 |
| 3 | Technic Axle and Pin Connector Angled #2 - 180° | Black | 32034 | 6271869 | €0,11 |
| 6 | Technic Pin Long with Friction Ridges Lengthwise and Stop Bush [3 Lateral Holes, Big Pin Hole] | Light Bluish Gray | 32054 | 4211865 | — |
| 6 | Technic Axle 2 Notched | Red | 32062 | 4142865 | €0,07 |
| 4 | Technic Beam 1 x 6 Thin | Yellow | 32063 | 6170294 | €0,13 |
| 1 | Technic Axle 5 | Light Bluish Gray | 32073 | 4211639 | €0,11 |
| 5 | Technic Bush 1/2 Smooth with Axle Hole Semi-Reduced | Yellow | 32123b | 6271167 | €0,04 |
| 2 | Technic Axle and Pin Connector Toggle Joint Smooth | Black | 32126 | 6457112 | €0,25 |
| 6 | Technic Beam 2 x 4 L-Shape Thick | Yellow | 32140 | 6271828 | €0,15 |
| 2 | Technic Beam 2 x 4 L-Shape Thick | Black | 32140 | 6271825 | €0,15 |
| 5 | Technic Axle and Pin Connector Perpendicular 3L with Centre Pin Hole | Light Bluish Gray | 32184 | 6276969 | €0,12 |
| 1 | Technic Axle and Pin Connector Perpendicular 3L with Centre Pin Hole | Black | 32184 | 6276951 | €0,12 |
| 1 | Technic Gear 20 Tooth Bevel | Tan | 32198 | 6031962 | €0,56 |
| 6 | Technic Beam 3 x 5 L-Shape with Quarter Ellipse Thin | Black | 32250 | 6327162 | €0,42 |
| 3 | Technic Gear 12 Tooth Double Bevel | Black | 32270 | 4177431 | €0,18 |
| 4 | Technic Beam 1 x 9 Bent (7 - 3) Thick | Black | 32271 | 6276835 | €0,33 |
| 6 | Technic Beam 1 x 15 Thick | Dark Bluish Gray | 32278 | 4542576 | €0,42 |
| 5 | Technic Beam 1 x 5 Thick | Black | 32316 | 4142135 | €0,19 |
| 2 | Technic Beam 1 x 3 Thick | Black | 32523 | 4142822 | €0,10 |
| 5 | Technic Beam 1 x 3 Thick | Yellow | 32523 | 4153707 | €0,10 |
| 4 | Technic Beam 1 x 7 Thick | Yellow | 32524 | 4495934 | €0,25 |
| 1 | Technic Beam 1 x 7 Thick | Dark Bluish Gray | 32524 | 4495931 | €0,25 |
| 2 | Technic Beam 1 x 11 Thick | Yellow | 32525 | 6028107 | €0,33 |
| 5 | Technic Beam 1 x 11 Thick | Dark Bluish Gray | 32525 | 4603472 | €0,33 |
| 3 | Technic Beam 3 x 5 L-Shape Thick | Yellow | 32526 | 4144022 | €0,24 |
| 5 | Technic Beam 3 x 5 L-Shape Thick | Black | 32526 | 4142823 | €0,24 |
| 1 | Plate 1 x 3 | Red | 3623 | 362321 | €0,07 |
| 6 | Technic Axle 4 | Black | 3705 | 370526 | €0,08 |
| 1 | Technic Axle 6 | Red | 3706 | 6130002 | €0,12 |
| 1 | Plate 1 x 4 | Yellow | 3710 | 371024 | €0,12 |
| 1 | Technic Bush | Light Bluish Gray | 3713 | 6275844 | €0,05 |
| 2 | Technic Axle Pin without Friction Ridges Lengthwise | Tan | 3749 | 4666579 | €0,06 |
| 3 | Technic Connector Beam 3 x 3 | Black | 39793 | 6265644 | €0,38 |
| 4 | Technic Pin Long without Friction Ridges, with Anti-Roll Notch | Tan | 39888 | 6321305 | €0,08 |
| 4 | Technic Beam 1 x 9 Thick | Black | 40490 | 4645732 | €0,29 |
| 1 | Technic Beam 1 x 9 Thick | White | 40490 | 6001831 | €0,29 |
| 10 | Technic Beam 1 x 2 Thin | Black | 41677 | 6338428 | €0,13 |
| 4 | Technic Axle and Pin Connector Perpendicular Double Split | Light Bluish Gray | 41678 | 4211889 | — |
| 3 | Technic Driving Ring Connector Smooth [2 rounded and 2 flat side walls] | Light Bluish Gray | 42195 | 6273212 | €0,13 |
| 15 | Technic Pin 1/2 | Light Bluish Gray | 4274 | 4211483 | €0,05 |
| 63 | Technic Pin Long with Friction Ridges Lengthwise, 1 Center Slot | Black | 42924 | 6299413 | €0,10 |
| 14 | Technic Axle Pin with Friction Ridges Lengthwise | Black | 43093 | 4206482 | €0,06 |
| 1 | Technic Axle 7 | Yellow | 44294 | 6130009 | €0,16 |
| 1 | Hinge Plate 1 x 2 Locking with 1 Finger on Side, without Groove | Black | 44567b | 6266244 | €0,13 |
| 2 | Technic Pin Connector Perpendicular 2 x 2 Bent | Yellow | 44809 | 4195017 | — |
| 5 | Technic Pin Connector Hub with 2 Pins with Friction Ridges Lengthwise [Small Squared Pin Holes] | Light Bluish Gray | 44874 | 6321303 | €0,18 |
| 13 | Technic Axle 3 | Light Bluish Gray | 4519 | 4211815 | €0,05 |
| 1 | Brick Special 1 x 1 with Studs on 2 Sides | Red | 47905 | 6030266 | €0,11 |
| 1 | Slope 30° 1 x 1 x 2/3 (Cheese Slope) | Black | 54200 | 4504382 | €0,06 |
| 1 | Hinge Cylinder 1 x 2 Locking with 2 Click Fingers and Axle Hole, 7 Teeth | Black | 57360 | 6271535 | €0,13 |
| 1 | Light Cover 1 x 1 Round with Internal Bar / Bionicle Barraki Eye | Trans-Orange | 58176 | 6507868 | €0,07 |
| 1 | Technic Axle 5.5 with Stop [Rounded Short End] | Dark Bluish Gray | 59426 | 4508553 | €0,11 |
| 1 | Technic Axle Connector Smooth [with x Hole + Orientation] | Yellow | 59443 | 4519010 | €0,06 |
| 4 | Cone 1 x 1 [Top Groove] | Red | 59900 | 4529234 | €0,05 |
| 20 | Technic Beam 1 x 2 Thick with Pin Hole and Axle Hole | Dark Bluish Gray | 60483 | 6265093 | €0,07 |
| 1 | Technic Axle 9 | Light Bluish Gray | 60485 | 4535768 | €0,21 |
| 2 | Equipment Hose Nozzle / Gun with Side String Hole Simplified | Light Bluish Gray | 60849 | 4514195 | €0,12 |
| 38 | Technic Pin with Friction Ridges Lengthwise with No Center Slots | Black | 61332 | 6279875 | €0,06 |
| 4 | Slope 18° 2 x 1 x 2/3 with 4 Slots / Grate | Black | 61409 | 4541191 | €0,06 |
| 4 | Plate Round 1 x 1 with Solid Stud | White | 6141 | 614101 | €0,05 |
| 4 | Technic Universal Joint 3L [Complete Assembly] | Light Bluish Gray | 61903 | 6335279 | €0,74 |
| 1 | Technic Axle and Pin Connector Block 4 x 3 x 2 1/2 [Linear Actuator Holder] | Dark Bluish Gray | 61904 | 6356106 | €0,77 |
| 4 | Technic Pin Connector Round [Slotted] | Black | 62462 | 6173119 | €0,06 |
| 2 | Technic Axle and Pin Connector Perpendicular Triple | Black | 63869 | 6362991 | €0,17 |
| 4 | Technic Axle and Pin Connector Perpendicular Triple | Light Bluish Gray | 63869 | 6331441 | €0,17 |
| 1 | Technic Panel Fairing # 4 Small Smooth Long, Side B | Yellow | 64391 | 6533801 | €0,58 |
| 1 | Technic Panel Fairing # 3 Small Smooth Long, Side A | Yellow | 64683 | 6533795 | €0,58 |
| 4 | Technic Pin Long with Friction Ridges Lengthwise and Stop Bush [2 Lateral Holes, Small Pin Hole] | Red | 65304 | 6347789 | €0,13 |
| 8 | Technic Axle and Pin Connector Perpendicular | Black | 6536 | 6261371 | €0,10 |
| 5 | Technic Pin Connector Hub with 1 Pin with Friction Ridges Lengthwise [Square Holes] | Yellow | 65487 | 6282151 | €0,11 |
| 1 | Technic Pin Connector Hub Perpendicular 3L with 4 Pins (Squared Holes) | Light Bluish Gray | 65489 | 6282158 | €0,22 |
| 1 | Technic Gear 12 Tooth Bevel | Tan | 6589 | 4565452 | €0,10 |
| 2 | Technic Beam 1 x 3 Thin | Yellow | 6632 | 6344174 | €0,25 |
| 4 | Technic Beam 2 x 3 L-Shape with Quarter Ellipse Thick | Yellow | 71708 | 6332412 | €0,22 |
| 2 | Technic Beam 2 x 3 L-Shape with Quarter Ellipse Thick | Black | 71708 | 6326047 | €0,22 |
| 1 | Sticker Sheet for Set 42121-1 | Unknown | 72184 | 6323407 | — |
| 1 | Tile 2 x 4 with Groove | Yellow | 87079 | 4560181 | €0,16 |
| 2 | Technic Axle 4 with Stop | Dark Bluish Gray | 87083 | 6083620 | €0,07 |
| 4 | Plate Special 2 x 2 with Groove and Center Stud (Jumper) | Red | 87580 | 6126048 | €0,07 |
| 2 | Technic Linear Actuator Mini with Dark Bluish Gray Head and Orange Axle | Light Bluish Gray | 92693 | 6221464 | €2,44 |
| 1 | Technic Axle and Pin Connector Perpendicular Split | Light Bluish Gray | 92907 | 6279023 | €0,29 |
| 4 | Technic Gear 16 Tooth Reinforced [New Style] | Light Bluish Gray | 94925 | 4640536 | €0,21 |
| 2 | Tile Round 1 x 1 | Trans-Clear | 98138 | 6274738 | €0,05 |
| 1 | Tile Round 1 x 1 | Light Bluish Gray | 98138 | 6284071 | €0,04 |
| 4 | Technic Beam Triangle Thin [Type II] | Black | 99773 | 6331437 | €0,31 |

## Notes

- Track which of these parts you own and see what is missing: https://www.brickmissing.com/sets/42121-1-heavy-duty-excavator
- Inventory data is based on official LEGO inventories via the Rebrickable catalog, updated daily.
- Part images, minifigure lists and related sets are on the set page: https://www.brickmissing.com/sets/42121-1-heavy-duty-excavator