1970 Clark C60 7k forklift, Continental six motor. Eveything was working properly, fluids all at proper levels, then next morning NO TILT. Lift is fine. In researching our factory build manifest, two valves are listed. My immediate thought was that the control spool valve might have failed. But the tilt and lift spool valves are adjacent and part of the vavlve body casting, and lift funtions normally. Nothing visually evident when inspected. But the other valve listed in the build manifest is "Valve, Tilt Lock" (p/n 134371). Though adequately copmpetent with hydraulics, I had no previous experience with the tilt lock valve, though I understand its purpose. Google search for the part number brings up several different images of the part, none that are similar. One of them appears to be a mechanical screw-in valve (possibly spring actuated) that might be part of the control valve body, and might explain the cause of this sudden failure. Has anybody on this forum had experience or knowlege of this older machine? This one has a single lever for lift (up-down) and tilt (forward-back) operation. As always, many thanks for any useful information. -Tom
Part #137697 is for a CFY50 Clark. All are similar on the older trucks in C and C500 models. Basically an oblong block of steel (some may be cast) milled and ported to receive hyd pressure line, pass it thru to the cylinders then check valve them when pressure is dropped to hold the position. Innards are spring and seat to let go by and spring snap shut to hold. Just pull the thing and slowly disassemble on a work bench. It will be obvious how it functions and you will probable find a broken/jammed spring. A visit to a Clark dealer should get you a drawing of it and the internal part numbers from your build sheet as part #134371. Strange in, my 6 years with Clark and 14 in my own shop, never had one lock up. Occasionally one would not hold, and removal, examine, clean debris or replace the spring. Nash in Nicholasville, KY might help you with internal pieces.
Thanks for the reply! I have to pull the front cover this morning to get better access to the control valve and associated parts. I couldn't see the valve you pictured on earlier inspection, but now I know what to look for. Thanks again! -Tom
Some 2nd thoughts/... As I said; in years of being involved, only had a few ever give trouble. And never a lock up, only not hold. So, lets check some lead ins before we go to the trouble of disconnecting all those hoses to the valve. 1st. Trace your actual connecting linkage from the lever on column down to its connection with the valve spool. That it is not jammed, bound or loose and not opening the spool in the valve to give flow. 2nd. Trace the valve to tilt lock valve feed line. On old Clarks, were some rubber hoses that eventually trended to break down inside and plug themselves. Determine this line, disconnect it at the TLV and see that you actually have flow/pressure INTO the tilt lock valve. 3rd. If linkage is functioning, and you get flow/pressure from the hose into the valve, then apparently its the TLV. To reiterate, very unlikely. In it; and the ones we encountered, were a broken spring or metal debris in the system due to a pump going out and putting metal shards in the system and jamming the TLV. Sorry if I am late with this option...
To clarify, the tilt spool is centered and spring loaded to return to center in both directions. In other words, normal (like the lift spool which functions normally) with good linkage. The tilt is fully forward from bleed off and will not tilt back, no pulse or movement of the tilt hoses, and seemingly no hydraulic pressure from the tilt valve to the cylinders in either direction. I replaced seals in the tilt cylinders two years ago. I found the SM751 service manual mentioned by poster AresTech as a free PDF download which appears to be for later machines with different control valve arrangement that doesn't match mine (as it IS an older machine). I will pull the cowl cover a little later this morning, inspect and take a few pictures, then head over to my Clark dealer to see if I can get an internal diagram and parts listing for whatever lift lock valve I have. I'll also pull the hydraulic oil screen and filter to see if there's debris that may be causing a problem. Thanks again! -Tom
Think it in your "tilt" system, since I believe you said you still have lift. So if lift, you have pump, filter passage, that valve spool functioning. Check lift function; does it go up and bottom out to bypass. Means pump, filter open, valve working as should.
Lift funtion -normal. Tilt function feels normal on linkage and valve position, but no action at cylinders. -Tom
Here are some photos of what appears to be the tilt lock valve on my machine. In the third image down and viewing from the front, the two lines from the control valve tilt spool are on the left, the two lines from the two tee'ed tilt cylinders are on the right, and return is the center one. I'll verify pressures before pulling the valve itself. Note that none of the online pictures I've found so far for the "Valve, Tilt Lock" (p/n 134371) resemble mine, though I may not have found the correct link. -Tom
Self deleted, to complicated to offer in text.
That yoke is for throttle rod that extends to the rear of the motor (propane setup). Looking toward the back of the tilt lock valve just to the front (view from the back side of it). UPDATE: After getting the cowl cover off I was able to get a better view and access to the control valve and tilt lock valve plumbing. Though I had tested the cylinders earlier for any flow, I decided to disconnect the spool valve fitting on the control valve leading to the input of the TL valve to see if I had any pressure. No pressure at all from either the back or forward positions of the spool, though the adjacent lift spool is funtioning normally. Conclusion is the control valve has to come off and be resealed. I ordered the seal kit from my friendly Clark Dealer and am waiting for it to arrive. Meanwhile, I don't look forward to having to pull the control valve assembly, though it might be a little easier than if I had to pull the TL valve due to accessibility. Here's a couple of photos...
Glad you have it isolated, sorry for the job of installing the kit. As on old and steady hand, I would pull the lift spool out and kit it. Easy now with valve out than go back and do it again... Examine the contents of the kit, as that is not a Clark OEM valve. It may be mfg by the same company as made Clarks, but LPM did not exist then the truck was assembled.
Thanks for the tips! I had already started to remove the control valve for a rebuild, and have drained the hydraulic fluid to minimize the mess. The control valve part number matches the build manifest p/n and doesn't look like a replacement, and looks like its always been in the same place since the machine was a newborn. But I'll certainly be looking at seals to ensure they're correct. Also, our machine is a 1966 C70, not a 1970 C60 165. Battery acid had obliterated parts of the original serial number which is stamped on the casting just below the swinging battery tray, so I only had a partial number. I searched everywhere on the machine for another s/n location but couldn't find one. The original plate on the cowl cover was missing. After many searches and dead ends, I called Clark which put me in touch with someone with access to old build records who might be able to narrow down the correct s/n. The legible part of the stamped number is/was C70-165-797??. This narrowed the choices down to only two possibilities: A C70-165 built in 1966, or a C60-153 built in 1967. They emailed a copy of both machines and I compared the part numbers for all major assemblies including the control vavle, which for the most part, matched. The Continental six engine had been swapped with a rebuild sometime in the past as the build sheets for both machines have different engine s/n's Apparently, two versions of the same frame built to specific needs. The seal kit should arrive in a day or two, so I'm hoping my luck turns for the better! Thanks again, -Tom
The frame side stamp; and on the original data plate, is the only two places the SN will exist. If Clark narrowed it down to the two, then this: 1. Scrub the SN with paint thinner, good. Then gently sand with a fine grit emery cloth to cut a fine layer over the 797? area. Missing # has to be 0 to 9, as Clark makes SN up as C70 -- 165-- 797? C= Clark, 70 = capacity 7000, 165= trucks position in prod line, of the 797? production run. You have. (visible) C70-165-797?? Other possibility is: C60-153 built in 1967 Different capacity trucks. Yours is the top #. Post us a close up pic of that visible SN. Just would like to see. And it is a replacement. LPM did not exist back then.
Correction - Despite the C70 designation, the 153 indicates that this is the January 24 1967 ship date C60-153-797 build, sold to L.T.V. Aeronautics by a Dallas TX dealer. As I have the build manifests for it AND the other possible C70, the majority of major parts and accessories match the two. Battery acid has eaten away significant parts of the casting which made identification so difficult. Note this is stamped on the casting just to the right of the hydraulic tank breather cap. -Tom
I was puzzled by the LPM valve question I brought up, so I did some digging. Apparently LPM was set up in Chicago by Echlin, to handle forklift parts in conjunction with its NAPA ties. So it existed. But, When I quit Clark in 9/79 to open my own shop, there was no generally accepted knowledge of such a forklift parts supplier in the southeast. As I recall, it was in the early 80's when word spread of LPM, Intrupa, and another, offering access. However; knowing Clark's and any major manufacturers penchant for pricing, it would stretch the imagination of them buying from LPM when for years Vickers supplied them direct in valves and pumps. I have seen a lot of Clarks', but never with a identified after market source tab. OK, a question. Sometimes a truck was built as a C70 and stocked at the factory; but shipped to fill an order for a C60, or vice versa. Per Clark rules, docs, etc, they would have changed the counterweight to downgrade... Both same truck in vanilla except weight. The ones i have seen and known this done, all were noted on the "line card" (you call build/actual Machine Production Card), usually as a sort of memo like CWT # removed and # CWT replaced. If it showed a cwt number in the list, it would have been ----- thru and the replacement number entered, different font from card print. Look for any strike thru # or any memo verbiage down at the bottom, front or back.