Appellants challenge an order of the Philadelphia Court of Common Pleas granting appellee’s motion for judgment on the pleadings and dismissing appellants’ complaint. Because appellants filed their actions beyond the applicable period of limitations, 13 Pa.C.S.A. § 2725, we affirm.
The case arises from a March 17, 1981 truck accident that killed the driver of the truck, Kenneth B. Haines, and injured a passenger, appellant Robert L. Patton. At the time of the accident, both Mr. Haines and Mr. Patton were acting within the sсope of their employment with Chemical Leaman Tank Lines, Inc. Mr. Patton and his wife, appellant Esther P. Patton, instituted an action by writ of summons against the manufacturer of the truck, Mack Trucks, Inc. [Mack], on February 20, 1985. Appellant Joan M. Haines, administratrix of the estate of Mr. Haines, instituted a separate action against Mack on March 12, 1985. In their consolidated complaint, 1 appellants alleged that a de *4 fective steering mechanism caused the truck in which Mr. Haines and Mr. Patton were riding to spin out of control. Appellants further alleged that when Mack sold the truck to Chemical Leaman in 1977, it made express and implied warranties, which it breached by failing properly to design and manufacture the truck and its component steering mechanism.
The express warranty upon which appellants base their claim appeared on a Chemical Leaman purchase order form dated May 26, 1977. Chemical Leaman used the multipaged form to purchase the truck that injured Mr. Haines and Mr. Patton. The following warranty language was printed on the bottom of all but the first page: “Sellеr represents and warrants that all articles and services covered by this purchase order meet or exceed the regulations established and promulgated under the Federal Occupational Safety and Health Law, Public Law 91-596 ... in effect or proposed as of the date of this order.” 2 Appellants contended that the truck failed to meet applicable workplace safety standards. 3 In addition to this alleged breach, appellants claimed that Mack breached implied warranties оf merchantability and fitness for the particular purpose, which, unless excluded, apply to all sales of goods, see 13 Pa.C.S.A. §§ 2314-2316. The trial court nonetheless agreed *5 with appellee that the four-year statute of limitations on breach of warranty claims, 13 Pa.C.S.A. 2725, barred appellants’ causes of action. It therefore granted appellee’s motion for judgment on the pleadings. This timely appeal followed.
We must decide whether appellant’s causes of action for breach of warranty accrued in 1977, when Mack delivered the allegedly defective truck to Chemical Leaman, or in 1981, when the accident that injured Mr. Haines and Mr. Patton occurred. This task requires that we construe both the statute of limitations provision of the Commercial Code and the purchase agreement between Mack and Chemical Leaman. The Code provision reads as follows:
(a) General rule. — An action for breach of any contract for sale must be commenced within four years after the cause of action has aсcrued. By the original agreement the parties may reduce the period of limitations to not less than one year but may not extend it.
(b) Accrual of cause of action. — A cause of action accrues when the breach occurs, regardless of the aggrieved party’s lack of knowledge of the breach. A breach of warranty occurs when tender of delivery is made, except that where a warranty explicitly extends to future performance of the goods and discovery of the breach must await the time of such performance the cause of action accrues when the breach is or should have been discovered.
13 Pa.C.S. § 2725(a) and (b) (emphasis added). In the usual case under Section 2725, a cause of action for breach of warranty accrues when the seller tenders delivery to the buyer. An aggrieved party must bring suit within four years of tender regardless of whether he or she knows that a breach has occurred. The last sentence of Subsection 2725(b), however, extends the period of limitations in those few cases that meet the stated twofold test. If (1) the warranty “explicitly extends” to future performance of the goods and (2) discovery of the breach must await future performance, the cause of action accrues when “the breach
*6
is or should have been discovered.” We have cautioned that an extension of the usual period “will not be permitted except in those instances in which there is a clear and unambiguous expression of an intent that the warranty shall pertain to future performance.”
Ranker v. Skyline Corp.,
Apрellants contend that the warranties in question “explicitly extended” to future performance of the truck and that neither Mr. Haines nor Mr. Patton could have discovered the breach before the March 17, 1981 accident. Appellants therefore ask us to find that their causes of action accrued in 1981. If we so find, we would have to conclude that the trial court erred when it found appellants actions barred by the four year period of limitations. We address in order appellants’ four arguments in support of their рosition.
I.
Appellants argue that the grant of judgment on the pleadings precluded jury consideration of certain vaguely-identified “extrinsic facts and parol evidence.” These facts, they argue, would have established that the express warranty printed on the purchase order form “explicitly extended” to future performance of the truck. Appellants incorrectly assume, however, that construction of the warranty necessarily poses a jury question. This court has held that a grant of judgment on the pleadings “mаy be appropriate in cases that turn upon the construction of a written agreement.”
DiAndrea v. Reliance Savings and Loan Ass’n.,
*8
Appellants nonetheless rely on
Gonzalez v. U.S. Steel Corp.,
We have pointed out already that interpretation of the warranty in this case did not depend on extrinsic evidence. The warranty language was free of any patent or latent ambiguities. The court therefore correctly confined its inquiry to the four corners of the purchase order.
See Steuart v. McChesney,
II.
Appellants next contend that even if the trial court could interpret the express warranty as a matter of law and without the aid of a jury, it did so incorrectly in this case. Appellants insist that the trial court rendered the warranty language meaningless when it held that the warranty did not “implicitly extend” to future performance of the truck. They point out that Mack, in effect, warranted to provide Chemical Leaman employees with a workplace *9 that conformed to existing federal safety standards. Mack’s warranty had meaning, according to appellant’s analysis, only if it extended into the future to cover the period during which the truck actually served as a workplace for Chemical Leamаn employees. Appellants also insist that because Mr. Haines and Mr. Patton could not possibly have discovered the breach before the March 17, 1981 accident, the warranty necessarily extended to future performance. We disagree with these arguments.
Professors White and Summers have observed that “extension of the normal warranty period does not occur in the usual case, even though all warranties in a sense apply to future performance of goods.” J. White & R. Summer, Uniform Commercial Code § 11-9 (2d ed. 1980). Anоther expert has reasoned that Section 2725(b) “presumes that all warranties, expressed or implied, relate only to the condition of the goods at the time of sale.” Klinger, The Concept of Warranty Duration: A Tangled Web, 89 Dick. L.Rev. 935, 939 (1985). The drafters of the Commercial Code certainly understood that in most cases a warranty is tested only after the seller has put the goods to their intended use. Nonetheless, they established “tender of delivery” as the point at which the period of limitations begins to run. Actual discovery of the breach is irrelevant in the usual case. This strict rule ensures that the seller will not have to account for its product or wares beyond “the normal commercial record keeping period,” unless it explicitly agrees to do so. 13 Pa.C.S.A. § 2725, Uniform Commercial Code Official Comment. Section 2725 serves the interests of commercial uniformity and practicality even though it might bar some otherwise meritorious breach of warranty actions.
We therefore must reject the argument that a warranty necessarily extends to future performance merely because it contains рromises regarding the manner in which the goods will perform after tender of deliver. The same argument applies to nearly all warranties. If we held that the warranty in this case “explicitly extended” to future
*10
performance, we would allow the exception to swallow the rule. Commonplace warranties such as those which guarantee the number or quality of widgets a particular machine can produce or the number of pounds a particular truck can haul
6
all would “explicitly extend” to future performance. The drafters of the Code could not have intended this result. As we noted in
Ranker, supra
342 Pa.Superior Ct. at 515,
We must also reject the related argument that a warranty necessarily extends to future performance when the aggrieved party cannot possibly discover the breach until after tender of delivery. Appellants rely heavily on the reasoning in
Perry v. Augustine,
37 Pa.D. & C.2d 416 (Mercer 1965).
Perry
involved an allegedly defective heating system. The seller tendered delivery of the system in July, but had warranted that it would “be able to heat at 75° inside at a —20° outside temp.”
Perry,
37 Pa.D. & C.2d at 416. The court held that this warranty “explicitly extended” to future performance beсause discovery of a breach “would necessarily have to await winter weather.”
Id.
at 418. Appellants argue that the same rationale applies to this case. We certainly agree that Mr. Haines and Mr. Patton could not reasonably have ascertained the condition of the steering mechanism before it failed. Nonetheless, Section 2725(b) provides that a cause of action
*11
accrues “regardless of the aggrieved party’s lack of knowledge of the breach.”
See also Rufo v. Bastian-Blessing Co.,
III.
Appellants further argue that the trial court, in granting judgment on the pleadings, erroneously assumed that implied warranties of fitness and merchantability can never *12 “explicitly extend” to future performance. Appellants believe they could have proved to a jury that Mack’s implied warranties were explicitly prospective. The trial court, however, never expressly addressed this issue in its opinion. In appellants’ view, the court by its silence necessarily endorsed the proposition that the further performance exception of Section 2725(b) does not apply to implied warranties. We disagree with this interpretation of the trial court’s holding.
Appellants’ pleadings lack any allegations of fact that would place in issue whether Mack’s implied warranties “explicitly extended” to future performance of the truck. Appellants claim that they raised the issue in their “Memorandum of Law in Opposition to Defendant’s Motion for Judgment on the Pleadings.” As we noted earlier, however, when a court hears a motion for judgment on the pleadings, it must confine its inquiry to the pleadings and relevant documents. It cannot consider the contents of briefs and memoranda.
See Gallo, supra
*13
Appellants, however, cite
Klondike Helicopters, Ltd. v. Fairchild Hiller Corp.,
The plain language of Section 2725 applies to all warranties, whether expressed or implied.
See Williams v. West Penn Power Co.,
*14 IV.
Appellants last contend that the limitations period on Commercial Code warranty actions by noncontracting third parties should not accrue until discovery of the breach. Mr. Haines and Mr. Patton, appellants argue, were complete strangers to the purchase agreement between Mack and Chemical Leaman. They participated in neither the tender nor the acceptance of the truck in 1977. Unlike Mack and Chemical Leaman, Mr. Haines and Mr. Patton could nоt possibly have discovered at the time of tender the defect in the truck’s steering mechanism. Therefore, appellants maintain that if we start running the statutory clock against them from tender of delivery, we will preclude them from pursuing their breach of warranty remedies. This, they argue, will effectively restore the privity requirement that our supreme court so thoroughly eradicated in
Salvador v. Atlantic Steel Boiler Co.,
Appellants do not ask us to apply the statute of limitations for tort claims, 42 Pa.C.S.A. § 5524(2), with its attendant “discovery doctrine.” Our supreme court in Williams, supra, made clear that the four-year Commercial Code period of limitations applies to all breach of warranty claims regardless of the degree to which the aggrieved party is related to the seller or the sale. Appellants therefore acknowledge that the four-year statute applies 12 but ask us to cut out of whole cloth an exception to the usual tender-of-delivery accrual date. This we cannot do.
Section 2725(b), we repeat, renders lack of knowledge irrelevant to the usual case. The cause of action accrues “regardless of the aggrieved party’s lack of knowledge of the breach.” We simply cannot ignore the plain meaning of this language. See 1 Pa.C.S.A. § 1921(b). Moreover, the *15 official commentary to Section 2725 reveals that the drafters had the realities of modern business practice in mind when they penned the Commercial Code’s limitations provisions. In order to avoid the kind of uncertainty and lack of uniformity that would discourage commercial development, they expressly rejected a liberal discоvery rule. A seller in the usual case can expect to account for defects in his product at any time within the four years following tender of delivery. To require an accounting beyond this period, in the absence of an explicit extension, would, in the drafters’ view, unduly burden commerce. Thus, nothing in the plain language or purpose of Section 2725 justifies creation of an accrual-on-delivery exception for aggrieved parties who, like Mr. Haines and Mr. Patton, cannot possibly know the condition of goods at thе time of tender.
Williams v. West Penn Power Co., supra,
upon which appellants rely, does not affect our conclusion. In
Williams,
appellant urged that the lack of privity between appellant and appellee required application of the tort statute of limitations to appellant’s breach of warranty action. Our supreme court disagreed and adamantly reaffirmed the notion first set forth in
Salvador v. Atlantic Steel Boiler Co., supra,
that the concept of privity does not belong in breach of warranty cases. In his opinion for a unanimous court, then-Justice Nix concluded thаt “[t]he extension of liability under the Code to persons not in privity with those in the chain of manufacture and marketing does not validate the application of the tort statute of limitations.”
Williams, supra
V.
For the foregoing reasons, we affirm the order of the Philadelphia Court of Common Pleas granting aрpellee’s motion for judgment on the pleadings and dismissing appellants’ complaint.
Order affirmed.
Notes
. The parties stipulated to the consolidation of the Patton and the Haines actions, which the trial court approved on July 18, 1985. Pa.R.C.P. 2229(a) permits joinder of plaintiffs “who assert any right to relief ... arising out of the same transaction, occurrence, or series of transactions or occurrences if any common question of law or fact affecting the right to relief of all such persons will arise in the action."
. Appellants appended photocopies of the purchase order to their complaint and marked it "Exhibit A." The photocopying obscured some of the warranty language, but, fortunately, the portions critical to our review remained legible.
. Absent a pertinent regulation, the Secretary of Labor can enforce the so-called “General Duty Clause" of the Occupational Safety and Health Act of 1970, 29 U.S.C. § 654(a)(1), against employers who maintain unsafe workplaces.
See, e.g., Usery v. Marquette Cement Mfg. Co.,
. In Metzger, we held that a contract is "ambiguous”
if, and only if, it is reasonably or fairly susceptible of different constructions and is capable of being understood in more senses than one and is obscure in meaning through indefiniteness of expression or has a double meaning. A contract is not ambiguous if the court can determine its meaning without any guide other than a knowledge of the simple facts on which, from the nature of language in general, its meaning depends; and a contract is not rendered ambiguоus by the mere fact that the parties do not agree upon the proper construction.
. Of course, we cannot take into account "allegations" in the pleadings that amount to nothing more than conclusions of law. In determining whether a case is ripe for disposition on the pleadings, we consider only whether unknown or disputed issues of
fact
are present.
See Del Quadro v. City of Philadelphia,
. See, for example, the warranty at issue in Conlan v. Ford Motor Co., 5 Pa.D. & C.3d 243 (Phila.1978).
. We do not hold that this “clear and unambiguous expression" must appear on the face of the agreement. Under 13 Pa.C.S.A. § 2313, the warranty itself need not appear in written form. We therefore find no reason why the "explicit extension” оf the warranty should so appear.
. In
O’Brien,
appellant claimed that her mother, while pregnant with appellant in 1956, had taken a drug manufactured by appellees. This allegedly cause appellant to contract cancer as a teenager. In Part IV of his opinion, Judge Aldisert concluded that Section 2725 barred appellant’s breach of warranty claim.
See O’Brien,
. For examples of explicitly prospective warranties, see
Commissioners of Fire District No. 9 v. American La France,
. We note, however, that "courts generally have held that the implied warranties of merchantability and fitness for a particular purpose cannot
explicitly
relate to future performance."
Klinger, supra
at 938 (emphasis in original).
See also
J. White & R. Summers,
supra
at
*13
§ 11-9 n. 73 (“implied warranty by nature cannot be explicit”). This, apparently, is the majority view among courts that have considered the issue.
See e.g., Holdridge v. Heyer-Schulte Corp. of Santa Barbara,
. The court did not consider whether the future performance exception can ever apply to implied warranties. But see note 10 supra.
. Of course, the two-year period of limitations for tort claims would not help appellants, even if it were to run from the date of discovery. Appellants did not file their actions within two years of the March 17, 1981 accident.
