Cat D7 Series Dozer Hydraulic Cylinders
This category covers blade lift cylinders, tilt cylinders, complete cylinder groups, cylinder tubes, and seal kits for Caterpillar D7 series crawler dozers — spanning the cable-era D7G, the elevated-sprocket D7H, and the finger-tip-control D7R, D7R II, and D7R XR. These are big, high-pressure cylinders that push heavy SU, U, and angle blades, so getting the right one starts with your model and blade configuration. Broken Tractor stocks complete cylinder groups, replacement tubes, and rebuild components ready to ship.
Fits Models At A Glance
7A, D7G, D7H, D7R, D7R II, D7R XR, D7R2 — with older D7, D7C, D7D, D7E, and D7F machines served through cylinder-group and casting numbers
Fitment note: Verify your serial number and blade configuration (SU, U, S, or PAT) before ordering. On the D7G and earlier machines, the cylinder casting number stamped on the tube is the fastest way to match the right part.
What's In This Category
Complete Cylinder Groups — D7H & D7R
Cylinder group for the D7H (4T8639) and the shared cylinder group for the D7H, D7R, D7R II, D7R XR, and D7R2 (1291908). These are the complete blade cylinder assemblies for the elevated-sprocket and finger-tip-control machines — the workhorses of the modern D7 line.
Cylinder Tubes
Hydraulic cylinder tube for the D7H, D7R, D7R II, and D7R XR (1291910), and the semi-finished cylinder tube for the 7A and D7G (7J3337). Replace the tube when the bore is scored but the rod, gland, and piston are still serviceable — a big cost saver on these large cylinders.
Fitment Tip
The D7 line splits cleanly into two eras. The D7G and older machines (D7, D7C, D7D, D7E, D7F) use the earlier cylinder design — the 7J3337 semi-finished tube covers the 7A and D7G, and older blade cylinders like the 9J8748 tilt cylinder (3" rod, 6-1/2" bore, all serial numbers) carry their own casting numbers. The D7H, D7R, D7R II, and D7R XR use the modern high-drive cylinder groups (4T8639, 1291908) and share the 1291910 tube. Before ordering, confirm your blade type — SU (semi-universal), U (universal), S (straight), or PAT (power-angle-tilt) — since blade setup affects which cylinder group you need. The D7 serial number is on the rear of the machine, left side, high on the frame rail (it may be hidden by a ripper). Call us with your serial and blade configuration and we'll confirm the right cylinder before you buy.
Frequently Asked Questions
My Cat D7H blade won't lift even after rebuilding the lift cylinders — what else could it be?
If you've rebuilt the D7H lift cylinders and checked the valve linkage but the blade still barely moves — while the rippers lift fine and tilt works normally — the problem is usually in the control valve, not the cylinders. A common culprit is the 4T1860 shuttle valve group inside the control valve, located partially behind the centering spring cap. If the blade holds after it settles but responds slowly, inspect the shuttle valve and control valve spool before condemning the cylinders again.
What cylinder group fits my Cat D7R, D7R II, or D7R XR?
The complete cylinder group 1291908 fits the D7H, D7R, D7R II, D7R XR, and D7R2. If your cylinder bore is scored but the rest of the cylinder is good, the matching hydraulic cylinder tube is 1291910. Confirm your blade configuration (SU, U, S, or PAT) before ordering, since blade setup affects the correct cylinder.
Can I get a tilt cylinder seal kit for my Cat D7G dozer?
Yes. The D7G tilt cylinder seal kit fits cylinder number 9J8748 and covers all serial numbers. That cylinder uses a 3" rod and 6-1/2" bore. If the rod and bore are still smooth, a seal kit rebuild is far cheaper than replacing the complete cylinder. For the D7G blade cylinder tube, the 7J3337 semi-finished tube covers the 7A and D7G.
How do I tell a D7G cylinder from a D7H or D7R cylinder?
The D7G is a cable-and-older-hydraulic machine that uses the earlier cylinder design (7J3337 tube, 9J8748-style cylinders), while the D7H, D7R, D7R II, and D7R XR are elevated-sprocket machines using the modern cylinder groups (4T8639, 1291908) and the 1291910 tube. The two eras don't interchange. If you're unsure which you have, check the casting number stamped on the cylinder tube and match that rather than guessing from the machine model alone.
Why does my Cat D7 blade drift down when I leave it raised?
Blade drift on a D7 is most often caused by worn internal seals in the lift cylinders or a leaking control valve. To isolate it, plug the cylinder ports and pressure-test the cylinders individually — if they hold pressure when plugged but drift when reconnected, the leak is in the control valve, not the cylinders. If the cylinders bypass internally, a seal kit rebuild will restore blade hold as long as the bore and rod aren't scored.
Where is the serial number on a Cat D7 dozer?
On the D7 and other larger Cat dozers, the serial number is on the rear of the machine, left side, high up on the end of the left frame rail — it may be partly hidden by a ripper attachment. Pre-2001 machines use an 8-digit serial like 2RG04147; 2001 and newer machines use a 17-digit VIN. You need this number, along with your blade configuration, to order the correct cylinder or cylinder group.
Not sure which cylinder, tube, or seal kit fits your machine? Call or text us at (800) 909-7060 or submit a parts request and we'll match it to your serial number and blade setup.
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